• Journal of Digital Convergence
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• v.10 no.10
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• pp.301-306
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• 2012

We propose a method for accurate image acquisition in a machine vision system in the present study. The most important feature is required by the various lenses to implement real and of the same high quality image-forming optical role. The input of the machine vision system, however, is generated due to the aberration of the lens distortion. Transformation defines the relationship between the real-world coordinate system and the image coordinate system to solve these problems, a mapping function that matrix operations by calculating the distance between two coordinates to specify the exact location. Tolerance Focus Lens caused by the lens aberration correction processing to Galvanometer laser precision machining operations can be improved. Aberration of the aspheric lens has a two-dimensional shape of the curve, but the existing lens correction to linear time-consuming calibration methods by examining a large number of points the problem. How to apply the Bilinear interpolation is proposed in order to reduce the machining error that occurs due to the aberration of the lens processing equipment.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.57-65
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• 2004

Introduction : The phantom that includes high density materials such as steel was custom-made to fix lung and bone in order to evaluation inhomogeneity correction at the time of conducting radiation therapy to treat lung cancer. Using this, values resulting from the inhomogeneous correction algorithm are compared on the 2 and 3 dimensional radiation therapy planning systems. Moreover, change in dose calculation was evaluated according to inhomogeneous by comparing with the actual measurement. Materials and Methods : As for the image acquisition, inhomogeneous correction phantom(Pig's vertebra, steel(8.21g/cm3), cork(0.23 g/cm3)) that was custom-made and the CT(Volume zoom, Siemens, Germany) were used. As for the radiation therapy planning system, Marks Plan(2D) and XiO(CMS, USA, 3D) were used. To compare with the measurement value, linear accelerator(CL/1800, Varian, USA) and ion chamber were used. Image, obtained from the CT was used to obtain point dose and dose distribution from the region of interest (ROI) while on the radiation therapy planning device. After measurement was conducted under the same conditions, value on the treatment planning device and measured value were subjected to comparison and analysis. And difference between the resulting for the evaluation on the use (or non-use) of inhomogeneity correction algorithm, and diverse inhomogeneity correction algorithm that is included in the radiation therapy planning device was compared as well. Results : As result of comparing the results of measurement value on the region of interest within the inhomogeneity correction phantom and the value that resulted from the homogeneous and inhomogeneous correction, gained from the therapy planning device, margin of error of the measurement value and inhomogeneous correction value at the location 1 of the lung showed $0.8\%$ on 2D and $0.5\%$ on 3D. Margin of error of the measurement value and inhomogeneous correction value at the location 1 of the steel showed $12\%$ on 2D and $5\%$ on 3D, however, it is possible to see that the value that is not correction and the margin of error of the measurement value stand at $16\%$ and $14\%$, respectively. Moreover, values of the 3D showed lower margin of error compared to 2D. Conclusion : Revision according to the density of tissue must be executed during radiation therapy planning. To ensure a more accurate planning, use of 3D planning system is recommended more so than the 2D Planning system to ensure a more accurate revision on the therapy plan. Moreover, 3D Planning system needs to select and use the most accurate and appropriate inhomogeneous correction algorithm through actual measurement. In addition, comparison and analysis through TLD or film dosimetry are needed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.139-146
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• 2023

Maritime object detection systems, which detects small maritime obstacles such as fish farm buoys and visualizes distance and direction, is equipped with a 3-axis gimbal to compensate for errors caused by hull motion, but there is a limit to distance error corrections necessitated by the vertical movement of the camera and the maritime object due to wave motions. Therefore, in this study, the distance error of maritime object detection systems caused by the movement of the water surface according to the external environment is analyzed and corrected using average filter and moving average filter. Random numbers following a Gaussian standard normal distribution were added to or subtracted from the image coordinates to reproduce the rise or fall of the buoy under irregular waves. The distance calculated according to the change of image coordinates, the predicted distance through the average filter and the moving average filter, and the actual distance measured by laser distance meter were compared. In phases 1 and 2, the error rate increased to a maximum of 98.5% due to the changes of image coordinates due to irregular waves, but the error rate decreased to 16.3% with the moving average filter. This error correction capability was better than with the average filter, but there was a limit due to failure to respond to the distance change. Therefore, it is considered that use of the moving average filter to correct the distance error of the maritime object detection system will enhance responses to the real-time distance change and greatly improve the error rate.

• Journal of Korea Multimedia Society
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• v.8 no.10
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• pp.1360-1368
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• 2005

PDP is the flat panel display, suitable for high definition television because of large-sire and high-brightness. It has many advantages such as fast response, wide viewing angle, low weight, and simple manufacturing process for fabrication. However, there are some disadvantages and one of them is the image quality degradation, which is dependent on the digital signal processing. Although image quality of PDP is improving by many researches and experimentations, it still isn't as good as that of CRT because of various factors. One of them is worm-like pattern generated by an error diffusion process. And the worm-like pattern is severely increased after an APL process. An increased worm-like pattern occur a drop of resolution in image and a change of CCT according to each grayscale. In this paper, a method for improvement of image quality using the error diffusion which considers the APL process is proposed. In the proposed method, the APL process is performed before the error diffusion process. Simulation results showed that the proposed method has better performances for resolution in images and CCT uniformity according to each grayscale than the conventional method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.319-322
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• 2001

The proposed system was composed of pre-processor which was executing binary/high-pass filtering and post-processor which ranged from statistic data to prediction. In post-processor work, step one was filter process of image, step two was image recognition, and step three was destruction degree/time prediction. After these processing, we could predict image of the last destruction timestamp. This research was produced variation value according to growth of tree pattern. This result showed improved correction, when this research was applied image Processing. Pre-processing step of original image had good result binary work after high pass- filter execution. In the case of using partial discharge of the image, our research could predict the last destruction timestamp. By means of experimental data, this Prediction system was acquired ${\pm}$3.2% error range.

• Journal of Korea Society of Industrial Information Systems
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• v.21 no.5
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• pp.11-17
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• 2016

In this paper, we propose a method of correcting depth image by the plane modeling and then improving the coding performance. We model a plane by using the least squares method to the horizontal and vertical directions including the target pixel, and then determine that the predicted plane is suitable from the estimate error. After that, we correct the target pixel by the plane mode. The proposed method can correct not only the depth image composed the plane but also the complex depth image. From the simulation result that measures the entropy power, which can estimate the coding performance, we can see that the coding performance by the proposed method is improved up to 80.2%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.1
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• pp.26-33
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• 2001

The proposed system was composed of pre-processor which was executing binary/high-pass filtering and post-processor which ranged from statistic data to prediction. In post-processor work, step one was filter process of image, step two was image recognition, and step three was destruction degree/time prediction. After these processing, we could predict image of the last destruction timestamp. This research was produced variation value according to growth of tree pattern. This result showed improved correction, when this research was applied image Processing. Pre-processing step of original image had good result binary work after high pas- filter execution. In the case of using partial discharge of the image, our research could predict the last destruction timestamp. By means of experimental data, this prediction system was acquired $\pm$3.2% error range.

• Progress in Medical Physics
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• v.11 no.1
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• pp.39-47
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• 2000

In Stereotactic Radiosurgery (SRS), there are three imaging methods of target localization, such as digital subtraction Angiography (DSA), computed tomography (CT), magnetic resonance imaging (MRI). Especially, DSA and MR images have a distortion effect generated by each modality. In this research, image properties of DSA were studied. A first essential condition in SRS is an accurate information of target locations, since high dose used to treat a patient may give a complication on critical organ and normal tissue. Hut previous localization program did not consider distortion effect which was caused by image intensifier (II) of DSA. A neurosurgeon could not have an accurate information of target locations to operate a patient. In this research, through distortion correction, we tried to calculate accurate target locations. We made a grid phantom to correct distortion, and a target phantom to evaluate localization algorithm. The grid phantom was set on the front of II, and DSA images were obtained. Distortion correction methods consist of two parts: 1. Bilinear transform for geometrical correction and bilinear interpolation for gray level correction. 2. Automatic detection method for calculating locations of grid crosses, fiducial markers, and target balls. Distortion was corrected by applying bilinear transform and bilinear interpolation to anterior-posterior and left-right image, and locations of target and fiducial markers were calculated by the program developed in this study. Localization errors were estimated by comparing target locations calculated in DSA images with absolute locations of target phantom. In the result, the error in average with and without distortion correction is $\pm$0.34 mm and $\pm$0.41 mm respectively. In conclusion, it could be verified that our localization algorithm has an improved accuracy and acceptability to patient treatment.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.1
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• pp.1-5
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• 2007

Purpose: The accuracy and advantages of OBI(On Board Imager) against the conventional method like film and EPID for the setup error correction were evaluated with the analysis of the accumulated data which were produced in the process of setup error correction using OBI. Materials and Methods: The results of setup error correction using OBI system were analyzed for the 130 patients who had been planned for 3 dimensional conformal radiation therapy during March 2006 and May 2006. Two kilo voltage images acquired in the orthogonal direction were fused and compared with reference setup images. The setup errors in the direction of vertical, lateral, longitudinal axis were recorded and calculated the distance from the isocenter. The corrected setup error were analyzed according to the lesion and the degree of shift variations. Results: There was no setup error in the 41.5% of total analyzed patients and setup errors between 1mm and 5mm were found in the 52.3%. 6.1% patients showed the more than 5mm shift and this error were verified as a difference of setup position and the movement of patient in a treatment room. Conclusion: The setup error analysis using OBI in this study verified that the conventional setup process in accordance with the laser and field light was not enough to get rid of the setup error. The KV images acquired using OBI provided good image quality for comparing with simulation images and much lower patients' exposure dose compared with conventional method of using EPID. These advantages of OBI system which were confirmed in this study proved the accuracy and priority of OBI system in the process of IGRT(Image Guided Radiation Therapy).

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.505-508
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• 2000

The success of target reconstruction in SAR(Synthetic Aperture Radar) imaging system is greatly dependent on the coherent detection. Primary causes of incoherent detection are uncompensated target or sensor motion, random turbulence in propagation media, wrong path in radar platform, and etc. And these appear as multiplicative phase error to the echoed signal, which consequently, causes fatal degradations such as fading or dislocation of target image. In this paper, we present iterative phase error estimation scheme which uses echoed data in all temporal frequencies. We started with analyzing wave equation for one point target and extend to overall echoed data from the target scene - The two wave equations governing the SAR signal at two temporal frequencies of the radar signal are combined to derive a method to reconstruct the complex phase error function. Eventually, this operation attains phase error correction algorithm from the total received SAR signal. We verify the success of the proposed algorithm by applying it to the simulated spotlight-mode SAR data.