• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.665-671
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• 2020

MPEG-I is actively working on standardization on the coding of immersive video which provides up to 6 degree of freedom (6DoF) in terms of viewpoint. 3DoF+ video, which provides motion parallax to omnidirectional view of 360 video, renders a view at any desired viewpoint using multiple view videos acquisitioned in a limited 3D space covered with upper body motion at a fixed position. The MPEG-I visual group is developing a test model called TMIV (Test Model for Immersive Video) in the process of development of the standard for 3DoF+ video coding. In the TMIV, the redundancy between a set of input view videos is removed, and several atlases are generated by packing patches including the remaining texture and depth regions into frames as compact as possible, and coded. This paper presents an atlas generation method that removes small-sized blocks in the atlas for more efficient 3DoF+ video coding. The proposed method shows a performance improvement of BD-rate bit savings of 0.7% and 1.4%, respectively, in natural and graphic sequences compared to TMIV.

• Smart Media Journal
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• v.3 no.1
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• pp.52-62
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• 2014

Prevalence of common three-dimensional display progresses, increasing the demand for three-dimensional content. Starting from the year 2010 to meet increasing 2D to 3D conversion is insufficient to meet demand content was presented as an alternative. But, Convert 2D to 3D stereo effect only emphasizes content production as a three-dimensional visual fatigue and the degradation of the Quality problems are pointed out. In this study, opened in 2011 'Scenes Guan', the 13 selected Scene is made of the three-dimensional transform the content and the Quality of the transformation applied to the Depth-Map is a visual representation of three-dimensional fatigue and, the adequacy of whether the expert has group interviews and surveys were conducted. Many of the changes are applied to the motion picture of the three-dimensional configurations of Depth-Map conversion technology used in many ways before and after the analysis of the relationship of cascade configurations to create a depth map to the stage. Experiments, presented in this study is a three-dimensional configuration of Depth-Map transformation can lower the production of a three-dimensional visual fatigue and improve the results obtained for a reasonable place was more than half of the experiment accepted the expert group to show a positive reaction were. The results of this study with a rapid movement to convert 2D images into 3D images of applying Depth-map configuration cascade manner to reduce the visual fatigue, to increase the efficiency, and has a three-dimensional perception is the result derived.

• Journal of radiological science and technology
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• v.39 no.1
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• pp.71-79
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• 2016

The purpose of this study is computed tomography contrast agent at low concentrations and low tube voltage technique to evaluate the usefulness on the phantom image. By varying the degree of mixture by the contrast medium concentration it was inserted in phantom. It was taken by changing the tube voltage and tube current step by step, and to evaluate the dose and the CT value obtained from the phantom image. As a result, low-contrast, low tube voltage(300 mgI/ml, 100 kV) was reduced by an average 21%(CTDIvol; computed tomography dose indexvol) more standard condition(350 mgI/ml, 120 kV). SNR was increased at all depths of the phantom, respectively 1:10 and 1:20(by diluting a contrast agent and normal saline) 12.2(26%) 6.2(17%). CNR was increased at all depths of the phantom, respectively 1:10 and 1:20(by diluting a contrast agent and normal saline) 11.5(32%), 6.3(26%). Research work on the CT scan is necessary in a variety of studies on the low contrast concentration and low tube voltage techniques for dose reduction and reducing of side effects the contrast agent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.158-165
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• 2019

Although evaluation of writing disabilities identification and timely intervention are required, clinicians adopt a manual scoring method and there is a possibility of error due to subjective evaluation. In this study, the size ratio and position of letters are digitized and quantified through image processing of offline handwritten characters. We tried to evaluate objectively and accurately the performance of writing through comparison with existing methods. From November 12th to 16th, 2018, 20 adults without neurological injury were selected. They used a pencil to follow the 10 words, 2 sentence stimuli after keeping the usual habit, and we collected the writing test data. The results showed that the height of the word was 1.2 times larger than the width and it tilted to the lower left. The spacing interval was 9mm on average. In the Paired T test, a high correlation was showed between our system and existing methods in the word and sentence 2. This demonstrated the possibility as a testing tool. This study evaluated objectively and precisely writing performance of offline handwritten characters through image processing and provided preliminary data for performance standards. In the future, it can be suggested as a basic data on writing diagnosis of various ages.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.697-702
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• 2022

For imaging in positron emission tomography(PET), it is necessary to measure the position of the scintillation pixel interacting with the gamma rays incident on the detector. To this end, in the conventional system, a flood image of the scintillation pixel is obtained, the imaged area of each scintillation pixel is separated, and the position of the scintillation pixel is specified and acquired as a digital signal. In this study, a deep learning method was applied based on the signal formed by the photosensor of the detector, and a method was developed to directly acquire a digital signal without going through various procedures. DETECT2000 simulation was performed to verify this and evaluate the accuracy of position measurement. A detector was constructed using a 6 × 6 scintillation pixel array and a 4 × 4 photosensor, and a gamma ray event was generated at the center of the scintillation pixel and summed into four channels of signals through the Anger equation. After training the deep learning model using the acquired signal, the positions of gamma-ray events that occurred in different depth directions of the scintillation pixel were measured. The results showed accurate results at every scintillation pixel and position. When the method developed in this study is applied to the PET detector, it will be possible to measure the position of the scintillation pixel with a digital signal more conveniently.

• Journal of the Korean Orthopaedic Association
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• v.54 no.4
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• pp.293-301
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• 2019

Soft tissue masses of the extremities and torso are a common problem encountered by orthopaedic surgeons. Although these soft tissue masses are often benign, orthopaedic surgeons need to recognize the key features differentiating benign and malignant masses. An understanding of the epidemiology and clinical presentation of soft tissue masses is needed to develop a practical approach for evaluation and surgical management. Size and depth are the two most important factors on which triage decisions should be based. In a differential diagnosis of a tumor, it is important to know the characteristics of the soft tissue mass through detailed history taking and physical examinations before the diagnostic procedures. A variety of imaging studies, such as simple radiography, ultrasound, magnetic resonance imaging, positron emission tomography, computed tomography, bone scan, and angiography can be used to diagnose tumors. Know the ledge of advantages and disadvantages of each imaging study is essential for confirming the characteristics of the tumor that can be observed in the image. In particular, ultrasonography is convenient because it can be performed easily in an outpatient clinic and its cost is lower than other image studies. On the other hand, the accuracy of the test is affected by the skill of the examiner. A biopsy should be performed to confirm the tumor and be performed after all imaging studies have been done but before the final treatment of soft tissue tumors. When a biopsy is to be performed, careful attention to detail with respect to multidisciplinary coordination beforehand, cautious execution of the procedure to minimize complications, and expedient follow-up and referral to a musculoskeletal oncologist when appropriate, are essential.

• The Transactions of the Korea Information Processing Society
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• v.13 no.7
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• pp.326-334
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• 2024

Extra-oral imaging techniques such as Panoramic X-rays (PXs) and Cone Beam Computed Tomography (CBCT) are the most preferred imaging modalities in dental clinics owing to its patient convenience during imaging as well as their ability to visualize entire teeth information. PXs are preferred for routine clinical treatments and CBCTs for complex surgeries and implant treatments. However, PXs are limited by the lack of third dimensional spatial information whereas CBCTs inflict high radiation exposure to patient. When a PX is already available, it is beneficial to reconstruct the 3D oral structure from the PX to avoid further expenses and radiation dose. In this paper, we propose 3DentAI - an U-Net based deep learning framework for 3D reconstruction of oral structure from a PX image. Our framework consists of three module - a reconstruction module based on attention U-Net for estimating depth from a PX image, a realignment module for aligning the predicted flattened volume to the shape of jaw using a predefined focal trough and ray data, and lastly a refinement module based on 3D U-Net for interpolating the missing information to obtain a smooth representation of oral cavity. Synthetic PXs obtained from CBCT by ray tracing and rendering were used to train the networks without the need of paired PX and CBCT datasets. Our method, trained and tested on a diverse datasets of 600 patients, achieved superior performance to GAN-based models even with low computational complexity.

• Journal of Biomedical Engineering Research
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• v.23 no.1
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• pp.49-60
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• 2002

Receive dynamic focusing with an array transducer can provide near optimum resolution only in the vicinity of transmit focal depth. A customary method to increase the depth of field is to combine several beams with different focal depths, with an accompanying decrease in the frame rate. In this Paper. we Present a simultaneous multiple transmit focusing method in which chirp signals focused at different depths are transmitted at the same time. These chirp signals are mutually orthogonal in a sense that the autocorrelation function of each signal has a narrow mainlobe width and low sidelobe levels. and the crossorelation function of any Pair of the signals has values smaller than the sidelobe levels of each autocorrelation function. This means that each chirp signal can be separated from the combined received signals and compressed into a short pulse. which is then individually focused on a separate receive beamformer. Next. the individually focused beams are combined to form a frame of image. Theoretically, any two chirp signals defined over two nonoverlapped frequency bands are mutually orthogonal In the present work. however, a tractional overlap of adjacent frequency bands is permitted to design more chirp signals within a given transducer bandwidth. The elevation of the rosscorrelation values due to the frequency overlap could be reduced by alternating the direction of frequency sweep of the adjacent chirp signals We also observe that the Proposed method provides better images when the low frequency chirp is focused at a near Point and the high frequency chirp at a far point along the depth. better lateral resolution is obtained at the far field with reasonable SNR due to the SNR gain in Pulse compression Imaging .

• Progress in Medical Physics
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• v.25 no.4
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• pp.264-270
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• 2014

This study developed a portable respiratory training device to improve breathing stability, which is an important element in using the CyberKnife Synchrony respiratory tracking device, one of the typical Stereotactic Radiation Therapy (SRT) devices. It produced an interface for users to be able to select one of two displays, a graph type and a bar type, supported an auditory system that helps them expect next respiration by improving a sense of rhythm of their respiratory period, and provided comfortable respiratory inducement. By targeting 5 applicants and applying individual respiratory period detected through a self-developed program, it acquired signal data of 'guide respiration' that induces breathing through signal data gained from 'free respiration' and an auditory system, and evaluated the usability by comparing deviation average values of respiratory period and respiratory amplitude. It could be identified that respiratory period decreased $55.74{\pm}0.14%$ compared to free respiration, and respiratory amplitude decreased $28.12{\pm}0.10%$ compared to free respiration, which confirmed the consistency and stability of respiratory. SBRT, developed based on these results, using the portable respiratory training device, for liver cancer or lung cancer, is evaluated to be able to help reduce delayed treatment time due to respiratory instability and improve treatment accuracy, and if it could be applied to developing respiratory training applications targeting an android-based portable device in the future, even use convenience and economic efficiency are expected.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.1
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• pp.19-31
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• 2005

Purpose : To supply the information of EPID system and to analyze the possibility of substitution EPID for film dosimetry. Materials & Methods : With amorphous silicon(aSi) type EPID and liquid filled lonization chamber(LC) type EPID, the reproducibility according to focus detector distance(FDD) change and gantry rotation was analyzed, and also the possible range of image acquisition was analyzed with Alderson Rando phantom. The resolution and the contrast of aSi type EPID image were analyzed through Las Vegas phantom and water phantom. DMLC image was analyzed with X-Omat V film and EPID to see wether it could be applied to the qualify assurance(QA) of IMRT. Results : The reproducibility of FDD position was within 1mm, but the reproducibility of gantry rotation was ${\pm}2,\;{\pm}3mm$ respectively. The resolution and the contrast of EPID image were affected by dose rate, image acquisition time, image acquisition method and frame number. According to the possible range of image acquisition of EPID, it is verified that the EPID is easier to use than film. There is no difference between X-Omat V film and EPID images for the QA of IMRT. Conclusion : Through various evaluation, we could obtain lots of useful information about the EPID. Because the EPID has digital data, also we found that the EPID is more useful than film dosimerty for the periodical Qualify Assurance of IMRT. Especially when it is difficult to do point dose measurement with diode or ionization chamber, the EPID could be very useful substitute. And we found that the diode and ionization chamber are difficult to evaluate the sliding window images of IMRT, but the EPID was more useful to do it.