• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.765-771
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• 2019

Noise in skull X-ray imaging is inevitable, which reduces imaging quality and diagnostic accuracy and increases errors due to the nature of digital imaging devices. Increasing the dose can attenuate noise, but that could lead to big problems with higher exposure dose received by patients. Thus, noise reduction algorithms are actively being studied at low doses to solve dose problems and reduce noise at the same time. Wiener filter and median filter have been widely used, with the disadvantages of poor noise reduction efficiency and loss of much information about imaging boundary. The purpose of this study is to apply total variation (TV) algorithm to skull X-ray imaging that can compensate for the problems of previous noise reduction efficiency to assess quantitatively and compare them. For this study, skull X-ray imaging is obtained using various kVp and mAs using the skull phantom using the X-ray device of Siemens. In addition, contrast to noise ratio (CNR) and coefficient of variation (COV) are compared and measured when noisy image, median filter, Wiener filter and TV algorithm were applied to each phantom imaging. Experiments showed that when TV algorithms were applied, CNR and COV characteristics were excellent under all conditions. In conclusion, we've been able to see if we can use TV algorithm to improve image quality and CNR could be seen to increase due to the decrease in noise as the amount of increased mAs. On the other hand, COV decreased as the amount of increased mAs, and when kVp increased, noise was reduced and the transmittance was increased, so COV was reduced.

• Progress in Medical Physics
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• v.25 no.1
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• pp.37-45
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• 2014

The accuracy and uniformity of CT numbers are the main causes of radiation dose calculation error. Especially, for the dose calculation based on kV-Cone Beam Computed Tomography (CBCT) image, the scatter affecting the CT number is known to be quite different by the object sizes, densities, exposure conditions, and so on. In this study, the scatter impact on the CBCT based dose calculation was evaluated to provide the optimal condition minimizing the error. The CBCT images was acquired under three scatter conditions ("Under-scatter", "Over-scatter", and "Full-scatter") by adjusting amount of scatter materials around a electron density phantom (CIRS062, Tissue Simulation Technology, Norfolk, VA, USA). The CT number uniformities of CBCT images for water-equivalent materials of the phantom were assessed, and the location dependency, either "inner" or "outer" parts of the phantom, was also evaluated. The electron density correction curves were derived from CBCT images of the electron density phantom in each scatter condition. The electron density correction curves were applied to calculate the CBCT based doses, which were compared with the dose based on Fan Beam Computed Tomography (FBCT). Also, 5 prostate IMRT cases were enrolled to assess the accuracy of dose based on CBCT images using gamma index analysis and relative dose differences. As the CT number histogram of phantom CBCT images for water equivalent materials was fitted with a gaussian function, the FHWM (146 HU) for "Full-scatter" condition was the smallest among the FHWM for the three conditions (685 HU for "under scatter" and 264 HU for "over scatter"). Also, the variance of CT numbers was the smallest for the same ingredients located in the center and periphery of the phantom in the "Full-scatter" condition. The dose distributions calculated with FBCT and CBCT images compared in a gamma index evaluation of 1%/3 mm criteria and in the dose difference. With the electron density correction acquired in the same scatter condition, the CBCT based dose calculations tended to be the most accurate. In 5 prostate cases in which the mean equivalent diameter was 27.2 cm, the averaged gamma pass rate was 98% and the dose difference confirmed to be less than 2% (average 0.2%, ranged from -1.3% to 1.6%) with the electron density correction of the "Full-scatter" condition. The accuracy of CBCT based dose calculation could be confirmed that closely related to the CT number uniformity and to the similarity of the scatter conditions for the electron density correction curve and CBCT image. In pelvic cases, the most accurate dose calculation was achievable in the application of the electron density curves of the "Full-scatter" condition.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.1
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• pp.73-83
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• 2011

The opening status of Saemangeum sluice gate is an important factor to the coastal water qualities near Saemangeum dikes. The sluice gate opening information is important in analysing current velocity and water quality data measured at the Saemanguem observation tower as well as in determining boundary conditions of numerical simulation for coastal environment outside Saemangeum dikes. This study establishes unmanned camera monitoring system on Saemangeum observation tower using mini notebook and digital camera, and extracts information on the opening status from images automatically. Images are analysed using variance difference of images together with edge detection techniques in order to get correct information.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.80-86
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• 2012

A fast maneuvering LEO satellite producing high resolution images was developed by Korea Aerospace Research Institute and launched successfully. To achieve accurate pointing and stringent pointing stability, the attitude orbit control subsystem implements high performance star trackers and gyroscopes. In addition, series of on-orbit calibration need to be performed to compensate mainly misalignment errors due to launch shock and on-orbit thermal environment. In this paper, the on-orbit calibration approach is described with the performance enhancement result through flight data analysis.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.6 no.2
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• pp.81-93
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• 2013

This review was described to investigate the feasibility of using ultrasound as an image tool for interventions of lumbar spine. This article will first provide an overview of lumbosacral spine surface anatomy and sonoanatomy. A detailed understanding of anatomy is critical for interpretation of ultrasound and procedural performance at spine. Fluoroscopy is most commonly used in interventional spine procedures, but radiation exposure is the major concern when obtaining fluoroscopic images. Ultrasound is radiation-free, is easy to use, and can provide real-time images with high accuracy. Also this device can be used in virtually any clinical setting. Ultrasound guidance offers a reliable alternative to fluoroscopy or computed tomography for lumbar interventions and can be safely performed without radiation exposure.

• Archives of Hand and Microsurgery
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• v.22 no.3
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• pp.137-146
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• 2017

Brachial plexus injury is regarded as one of the most devastating injuries of the upper extremity. Accurate diagnosis is important to obtain the successful results. Basic preoperative evaluation includes simple radiography, cervical myelography. Magnetic resonance imaging, angiography, electrophysiologic studies and intraoperative studies. Furthermore, proper timing of surgery, surgical indication, plan and sufficient understanding of patients about the prognosis are the key for the satisfactory outcomes. This article provides an overview of the evaluation, diagnosis, intraoperative monitoring, and proper surgical planning for the treatment of posttraumatic brachial plexus injuries.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.91-95
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• 2012

Purpose: In this study, we evaluated the ejection fraction (EF) according to the difference of patient position in Gated Blood Pool (GBP) scan. Material and Methods: The analysis was performed to 80 patients ($51.2{\pm}17.4$ years old) who examined GBP scan in Department of nuclear medicine, National Cancer Center from March 2011 to August 2011. We divided the patients into two groups; one group received conventional position (raise left arm up supine) and supine position (group 1) and the other group received conventional position and left arm back down supine position (group 2). To observe the change EF according to patient position difference, the image was reconstructed and analyzed by Xeleris (GE, USA). We measured body mass index (BMI) of patients. Result: In group 1, EF error less than 3% occurred at a rate of 72.5% (29 of the 40 patients). In group 2, EF error less than 3% occurred at a rate of 79% (32 of the 40 patients). The patient's BMI did not affect ejection fraction. Conclusion: The EF error of left arm back down supine position closer to conventional position than in supine position shows the results.

• Korean Journal of Remote Sensing
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• v.27 no.1
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• pp.9-15
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• 2011

Since PAN(panchromatic) and MS(multispectral) imagery of pushbroom scanner have the offset between PAN and MS CCD(charge coupled device) in the focal plane, PAN and MS images are acquired at different time and angle. Since clouds are fast moving objects, they should lead mis-registration problem with wrong matching points on clouds. The registration of cloudy imagery to recognize and remove the contamination of clouds can be categorized into three classes: (1) cloud is considered as nose and removed (2) employing multi-spectral imagery (3) using multi-temporal imagery. In this paper, method (1) and (3) are implemented and analysed with cloudy pushbroom scanner images.

• Journal of the Korea Computer Graphics Society
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• v.29 no.3
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• pp.127-135
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• 2023

Accurate segmentation of histopathology whole slide images (WSIs) is a crucial task for disease diagnosis and treatment planning. However, conventional automated segmentation algorithms may not always be applicable to WSI segmentation due to their large size and variations in tissue appearance, staining, and imaging conditions. Recent advances in interactive segmentation, which combines human expertise with algorithms, have shown promise to improve efficiency and accuracy in WSI segmentation but also presented us with challenging issues. In this paper, we propose a novel interactive segmentation method, ZoomISEG, that leverages multi-resolution WSIs. We demonstrate the efficacy and performance of the proposed method via comparison with conventional single-scale methods and an ablation study. The results confirm that the proposed method can reduce human interaction while achieving accuracy comparable to that of the brute-force approach using the highest-resolution data.

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.157-167
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• 2010

Density is the most important congestion indicator among the three fundamental flow variables, flow, speed and density. Measuring density in the field has two different ways, direct and indirect. Taking photos with wide views is one of direct ways, which is not widely used because of its cost and lacking of proper positions. Another direct density measuring method using two point detectors has been introduced with the concept of instantaneous density, average density and measurement interval. The relationship between accuracy and measurement interval has been investigated using the SIMULATION data produced by Paramics Application Programming Interface function. We analyze the affect of segment density accuracy by sensing gap each road condition such as sensing segment length, lane and LOS after gathering data by Paramics Application Programming Interface.