• Journal of Korea Water Resources Association
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• v.48 no.8
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• pp.659-672
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• 2015

In flow velocity measurement of natural rivers, taking images with proper image quality is the fundamental and the most important step. Since flood peaks generally occur in night time, it is very difficult to capture proper images in that time. The present study aims to test a far infra-red camera as a adequate alternative to resolve the various problems in measuring flood discharges. The far infra-red cameras are able to capture images in night time without help of any extra illuminations. Futhermore they are not affected by fog nor smoke, hence they can be adapted for a fixed-type surface image velocimeters. For comparison, a commercial camcorder and a near infra-red cameras were used together. The test images were taken at a day time and a night time, and the image acquisition work were performed at an artificial flow channel of the Andong River Experiment Station. The analyzed results showed that the far infra-red camera would be a good instrument for surface image velocimeters, since they were able to capture regardless light condition. There are, however, a few minor problems in their accuracy of the analyzed results. About their accuracy a more study would be required.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.143-147
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• 2016

Recently, digital tomosynthesis system (DTS) has been developed to reduce overlap using conventional X-ray and to overcome high patient dose problem using computed tomography (CT). The purpose of this study was to develop image reconstruction algorithm and to evaluate image characteristics and dose with chest digital tomosynthesis (CDT) system. Image reconstruction was used for filtered back-projection (FBP) methods and system geometry was constructed ${\pm}10^{\circ}$, ${\pm}15^{\circ}$, ${\pm}20^{\circ}$, and ${\pm}30^{\circ}$ angular range for acquiring phantom images. Image characteristics carried out root mean square error (RMSE) and signal difference-to-noise ratio (SDNR), and dose is evaluated effective dose with ${\pm}20^{\circ}$ angular range. According to the results, the phantom image with slice thickness filter has superb RMSE and SDNR, and effective dose was 0.166 mSv. In conclusion, we demonstrated usefulness of developed CDT image reconstruction algorithm and we constructed CDT basic output data with measuring effective dose.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.605-610
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• 2017

Unlike adults, cognitive ability and communication are not accurate in pediatric patients. Therefore movement due to psychological anxiety in X-ray photography is one of the factors that increase repeated irradiation. In order to minimize the rejection of X-ray and to improve the satisfaction of medical service, it is necessary to improve the environment of the radiological room to help psychological stability and to find a positive measure for reduction of radiation dose, including unnecessary. The subjects of this study were 186 pediatric patients from May to July, 2017, who were from 6 months to 36 months, The study group was set up a radiological room without auditory and visual environment changes is A group, except for changes in visual environment, the room where only auditory environmental changes were applied was group B, the auditory environment changes were excluded, and the room where only the visual environment change was applied was divided into group C, the auditory and visual environment changes were applied to the D. In group A, 10 retrospectives were obtained, 7 in group B, 5 in group C, and 2 in group D. Especially in group A and group D, statistically significant at p <0.053 In conclusion, hearing and visual environment changes affected the psychological stability of pediatric patient, and the repeated irradiation was reduced, thus improving the quality of medical services.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.2
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• pp.37-48
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• 2008

Generally, a motion vector and a disparity vector represent the motion information of an object in a single-view of camera and the displacement of the same scene between two cameras that located spatially different from each other, respectively. Conventional H.264/AVC does not use the disparity vector in the motion vector prediction because H.264/AVC has been developed for the single-view video. But, multi-view video coding that uses the inter-view prediction structure based on H.264/AVC can make use of the disparity vector instead of the motion vector when the current frame refers to the frame of different view. Therefore, in this paper, we propose an improved motion/disparity vector prediction method that consists of global disparity vector replacement and extended neighboring block prediction. From the experimental results of the proposed method compared with the conventional motion vector prediction of H.264/AVC, we achieved average 1.07% and 1.32% of BD (Bjontegaard delta)-bitrate saving for ${\pm}32$ and ${\pm}64$ of global vector search range, respectively, when the search range of the motion vector prediction is set to ${\pm}16$.

• Journal of Oral Medicine and Pain
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• v.24 no.2
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• pp.171-179
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• 1999

The authors experienced a oral carcinoma involving the medial cortex of the right ramus of mandible and the left side of the maxilla which was metastasized from primary rectal adenocarcinoma based on the comprehensive evaluation of data obtained from (1) the past medical history of primary rectal adenocarcinoma, (2) the computerized tomographic views of the homogeneous mass on the anteromedial region of the right ramus of mandible destructing the medial cortex of the right ramus of mandible, and the irregular mass around the clivus spreading into the sphenoid sinus and destructing the left side of the maxilla ; the bone scanning of hot spots on the nasal region and the left side of maxilla ; the posteroanterior chest radiographic view of multiple nodular radiopacities on the lung, (3) the retrospective review of the sonographic view of a hypoechoic, well-demarcated, target-like mass with central hyperechoic focus on right lobe of liver in a Korean female of 49-year-old who complained the ptosis of left eyelid, the swelling on left zygomatic area, the left facial paralysis, the facial asymmetry and a round-shaped, elevated lesion with a hematoma on the mucosa covering the right ramus of mandible.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.17-24
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• 2020

This study examined the spectral information and reflectance of cracks of an embankment with drone-based hyperspectral imagery for crack detection. A Nano-Hyperspec mounted on a drone was used as a sensor, and hyperspectral videos of different intensities of illumination of the cracks on the embankment located in the downstream of Andong-Dam were obtained. An analysis of the data value of the illumination and peak data-value, the coefficients of determination were calculated to be 0.9864 of the uncracked areas and 0.9851 of the cracked area. The reflectance of each area showed a similar value and pattern, regardless of the intensity of illumination. This result may have occurred because the reference values of the white reference as the calculation criteria of reflectance varied according to the intensity of illumination. The reflectance at the cracked area was 5.65% lower in visible light and 4.58% lower in near-infrared light than that at the uncracked area. The detection of cracks may offer more precise results in further studies when the gimbal direction and camera angles of the drone are calibrated. Because hyperspectral imagery enables the detection of crack depths and types of clay minerals, which are difficult to identify in general RGB imagery, it can serve as a preemptive measure for evaluating the embankment stability.

• Journal of Trauma and Injury
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• v.22 no.2
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• pp.142-147
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• 2009

Purpose: Early diagnosis and management of therapeutic interventions are very important in chest trauma. Conventional chest X-rays (CXR) and computed tomography (CT) are the diagnostic tools that can be quickly implemented for chest trauma patients in the emergency department. In this study, the usefulness of the CT as a diagnostic measurement was examined by analyzing the ability to detect thoracic injuries in trauma patients who had visited the emergency department and undergone CXR and CT. Methods: This study involved 84 patients who had visited the emergency department due to chest trauma and who had undergone both CXR and CT during their diagnostic process. The patients' characteristics and early vital signs were examined through a retrospective analysis of their medical records, and the CXR and the CT saved in the Picture Archiving Communication System (PACS) were examined by a radiologist and an emergency physician to verify whether or not a lesion was present. Results: Pneumothoraxes, hemothoraxes, pneumomediastina, pulmonary lacerations, rib fractures, vertebral fractures, chest wall contusions, and subcutaneous emphysema were prevalently found in a statistically meaningful way (p<0.05) on the CT. Even though their statistical significance couldn' be verified, other disorders, including aortic injury, were more prevalently found by CT than by CXR. Conclusion: CT implemented for chest trauma patients visiting the emergency department allowed disorders that couldn' be found on CXR to be verified, which helped us to could accurately evaluate patients.

• Journal of radiological science and technology
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• v.35 no.4
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• pp.309-314
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• 2012

Nowadays, digital Radiography (DR) systems are widely used in clinical sites and substitute the analog-film x-ray imaging systems. The resolution of DR images depends on several factors such as characteristic contrast and motion of the object, the focal spot size and the quality of x-ray beam, x-ray scattering, the performance of the DR detector (x-ray conversion efficiency, the intrinsic resolution). The DR detector is composed of an x-ray capturing element, a coupling element and a collecting element, which systematically affect the system resolution. Generally speaking, the resolution of a medical imaging system is the discrimination ability of anatomical structures. Modulation transfer function (MTF) is widely used for the quantification of the resolution performance for an imaging system. MTF is defined as the frequency response of the imaging system to the input of a point spread function and can be obtained by doing Fourier transform of a line spread function, which is extracted from a test image. In clinic, radiologic technologists, who are in charge of system maintenance and quality control, have to evaluate or make routine check on their imaging system. However, it is not an easy task for the radiologic technologists to measure MTF accurately due to lack of their engineering and mathematical backgrounds. The objective of this study is to develop and provide for radiologic technologists a medical system imaging evaluation tool, so that they can measure and quantify system performance easily.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.4
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• pp.351-357
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• 2008

An aerial multi-looking camera system equips itself with five separate cameras which enables acquiring one vertical image and four oblique images at the same time. This provides diverse information about the site compared to aerial photographs vertically. The geometric relationship of oblique cameras and a vertical camera can be modelled by 6 exterior orientation parameters. Once the relationship between the vertical camera and each oblique camera is determined, the exterior orientation parameters of the oblique images can be calculated by the exterior orientation parameters of the vertical image. In order to examine the exterior orientation of both a vertical camera and each oblique cameras in the multi-looking camera relatively, calibration targets were installed in a lab and 14 images were taken from three image stations by tilting and rotating a non-metric digital camera. The interior orientation parameters of the camera and the exterior orientation parameters of the images were estimated. The exterior orientation parameters of the oblique image with respect to the vertical image were calculated relatively by the exterior orientation parameters of the images and error propagation of the orientation angles and the position of the projection center was examined.

• Radiation Oncology Journal
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• v.5 no.2
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• pp.149-155
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• 1987

The success of radioation therapy depends on exact treatment of the tumor with significant high dose for maximizing local control and excluding the normal tissues for minimizing unwanted complications. To achieve these goals, correct estimation of target volume in three dimension, exact dose distribution in tumor and normal critical structures and correction of tissue inhomogeneity are required. The effect of therapy oriented CT (plannng CT) were compared with conventional simulation method in necessity of planning change, set dose, and proper distribution of tumor dose. Of 365 new patients examined, planning CT was performed in 104 patients $(28\%)$. Treatment planning was changed in $47\%$ of head and neck tumor, $79\%$ of intrathoracic tumor and $63\%$ of abdmonial tumor. in breast cancer and musculoskeletal tumors, planning CT was recommended for selection of adequate energy and calculation of exact dose to critical structures such as kidney or spinal cord. The average difference of tumor doses between CT planning and conventional simulation was $10\%$ in intrathoracic and intra-abdominal tumors but $20\%$ in head and neck tumors which suggested that tumor dose may be overestimated in conventional simulation Although some limitations and disadvantages including the cost and irradiation during CT are still criticizing, our study showed that CT Planning is very helpful in radiotherapy Planning.