• Journal of radiological science and technology
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• v.8 no.2
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• pp.3-9
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• 1985

From the study on the chest radiologic equipments and situations of university hospitals, general hospitals, and radiologic clinics located in Seoul area and Choong-cheong province, the author got conclusions as follows : 1. The rectfication methods of the equipments were employing mainly single or three-phase full wave, and 78% of the examined were using single phase full wave. 2. The focal sizes in case of small focus were less than 1.0mm in chest-only use, and more than 1.0mm in 81% of combined use. The focal sizes in case of large focus were more than 1.6mm in 78% of the total. 3. Maximum ratings of x-ray tubes were 47% at 125 kVp maximum tube voltage and 41% at 150kVp. The maximum tube currentes higher than 500mA were shown in 72% of all the examined. And the maximum exposure time was the range of 5-8sec. 4. Grid was not used in the 66% of all the hospitals. Equipment for chest-only was employing 10:1 grid ratio and the 2.0-2.9mmAl of total filtration formed 38% of all the examined. 5. In the processing time of exposed film, 68% of all was 90sec, and only 20% of all the examined used optimum developing temperature according to this condition. 6. In the radiographic conditions, more than 50% used low tube voltages lower than 70 kVp and only 3% of all the equipments used high tube voltages higher than 100 kVp. The 46.9% of all the equipments 300mA, and 53% of all used shorter exposure time less than 1/20(0.05) sec. 7. In the monthly average number of radiographs, 44% of all was x-ray the radiographs.

• Journal of Broadcast Engineering
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• v.15 no.3
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• pp.332-345
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• 2010

A unified image enhancement method is proposed for high-resolution image which based on color constancy and histogram equalization using edge region. To speed up the method, smaller image is used when parameters of color constancy and histogram equalization are determined. In the color constancy process, nth-derivative of gaussian is applied to x and y axis separately in order to estimate the color of the illumination rapidly. In the histogram equalization process, the histogram obtained from near-edge region is used for the histogram equalization. In the experiments, high-resolution images taken by digital camcorder are used for verifying the performance of the proposed method.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.121-124
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• 2015

Digital Mammography is very important for the early diagnosis of breast cancer. but excessive radiation dose to the patient may increase the probability of occurrence of breast cancer. absorbed dose rate and signal, noise, and contrast in accordance with the change of the filter, and analyzed the signal-to-noise ratio. absorbed dose rate GE Equipment is higher than that of Siemens and Hologic. using the material of Mo / Mo was lower than the other target-filter combination. SNR of Siemens equipment is high and measured high when Mo / Mo selected, the other two devices was measured high when Mo / Rh selected. when you choose a target-filter combination our results will be a good indicator.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.2
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• pp.323-330
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• 2019

Recently, as the growth of the Internet has led to a rapid increase in the consumption of multimedia such as photographs and moving images, the importance of metadata has been emphasized. In the case of existing metadata, only limited information such as GPS value or focal length according to the format is stored. However, with the development of mobile devices and multimedia acquisition devices, various sensors can be used in the devices. Therefore, this paper describes a method that can store not only the existing metadata format information at the time of multimedia acquisition but also another existing format of metadata such as information of various sensors which is the gyroscope and acceleration sensor of the device. We propose an application program that provides moving location information. The proposed method is expected to provide various applications such as image matching and effective image classification.

• Plant Journal
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• v.18 no.1
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• pp.50-54
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• 2022

The demand for high-efficiency dust collectors is rapidly increasing to remove PM from exhaust gas emission facilities, such as thermal power plants, steel mills, and industrial cogeneration plants, as the Pmemission standards have been strengthened. In this study, the electrospray is adapted for existing electrosratic precipitator(EP) to remedy its shortcomings and to improve the performance. Electrospray has been mainly used for the purpose of generating very fine droplets, but fir the purpose of EP, the flow rate over 10 mL/min per nozzleis required, and a high flow rate condition of 65 to 200 times is required. The electrospray of high flow rate has a completely different spray shape from the low flow rate condition, and was visualized through various figures such as corona discharge photographs and shadow images.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.619-625
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• 2022

In the field of imaging medicine, computed tomography is one of the most common test methods and one of the most frequently used test methods in hospitals. However, it is accompanied by a very high radiation exposure compared to other test methods. In order to reduce exposure, CT scans should be performed only when absolutely necessary, and even if the tests are performed because they are absolutely necessary, a protocol that serves the purpose of the test and allows the test to be performed in a small dose should be used. In this study, we wanted to learn about the most up-to-date radiation dose usage information used by the region's leading general hospitals and develop a diagnostic reference level (DRL). In the experimental results, the Head CT and Abdomen CT tests showed that DLP was higher than the NRPB (U.K) and Korean DRL. The DLP values used by Chest CT were low for all 3 types of CT devices. The hospital found that efforts to reduce exposure should be made during CT examinations, and in particular, Head CT and Abdomen CT determined that efforts to reduce exposure were necessary.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.307-314
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• 2011

This study proposed detection method of Marine debris using unmanned aerial photography. For unmanned aerial photography, a RC(Radio Control) helicopter which has good movability and economics was used. To a camera mounting, a gimbal equipment was attached to the bottom of the RC helicopter. The gimbal equipment is very useful because it is not seriously affected by vibration and rolling. In addition, we invented that digital image processing algorithm using Matlab program for detection of marine debris from photographs. Particularly, background subtraction in invented algorithm was applied. As a result, marine debris of a variety of forms from different sand states of coast were reliably detected. In the future, monitoring using proposed method was expected to contribute that the solution to representative problem of monitoring area selecting and estimate the total litter mass over the beach. Moreover, It is considered a greater application possibility to marine environmental observations.

• Journal of radiological science and technology
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• v.37 no.3
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• pp.195-201
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• 2014

The study examined the changes in the decreased facial exposure dose for radiological technologists depending on increased distance between the workers and the X-ray tube head during intraoral radiography. First, the facial phantom similar to the human tissues was manufactured. The shooting examination was configured to the maxillary molars for adults (60kVp, 10mA, 50msec) and for children (60kVp, 10mA, 20msec), and the chamber was fixed where the facial part of the radiation worker would be placed using the intraoral radiography equipment. The distances between the X-ray tube head and the phantom were set to 10cm, 15cm, 20cm, 25cm, 30cm, 35cm, and 40cm. The phantom was radiated 20 times with each examination condition and the average scattered doses were examined. The rate at the distance of 40cm decreased by about 92.6% to 7.43% based on the scattered rays radiated at the distance of 10cm under the adult conditions. The rate at the distance of 40cm decreased by about 97.6% to 2.58% based on the scattered rays radiated at the distance of 10cm under the children conditions. Protection from the radiation exposure was required during the dental radiographic examination.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.185-194
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• 2001

This study was designed to evaluate the effects of angulation changes of head posture on the enlargement ratios of a lateral headfilm depending on the vortical or horizontal rotation of the objects. A device was constructed to measure regional changes of enlargement ratios. The device was held within the cephalostat and cephalograms recorded at each measured degrees of the device tilting, vertically and horizontally. The enlargement ratios of the horizontal, vertical, and angular measurements on the films taken at each tilted angulations were obtained and compared with those on the films taken without rotation. In summary, the enlargement ratios of the horizontal linear measurements were decreased during horizontal rotations. The enlargement ratios of vortical measurements of the right side on the film were increased and those of the left side were decreased by the horizontal rotations. Enlargement ratios of horizontal measurements were affected further than those of vertical measurements by the same angular changes of the horizontal rotations. Therefore, a disruption of parallelism between the object's midsagittal plane and the film could result in distortion of the image while vertical rotation around the object's porionic axis would not significantly affect the enlargement ratios on the headfilm.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.433-438
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• 2015

To evaluate the radiation exposure level based on radiation workers' locations in dental radiography, the radiation dose rate in the radiographic room, lead glass, and operation system was measured. To that end, various devices were used, such as a Standard(Max-GLS, Shinhung), a panorama (PCH-2500, Vatech), a cephalometric radiography (PCH-2500), and a cone beam CT (PHT-30LFO, Vatech), as well as a PM1405 equipment as a radiation meter. Radiography conditions were set the same as the factors used in the clinical setting. As the result, the cone beam CT turned out the highest with 98 uSv and the standard showed the lowest level with 0.4 uSv/h. The panorama was measured to be higher than the Cephalo due to its different focus mode. On the lead glass surface and in the operation stand, the oral radiography device, panoramic, and Cephalo all were measured below the recording level. However, the cone beam CT was measured to have the leakage dose. Thus, radiation involved workers should be equipped with appropriate protection tools and reduce radiography time as much as possible. In addition, the structure of the radiation chamber should be also designed efficiently. Dental radiography has continued to grow in recent years, so it is necessary take appropriate protection measures for patients and radiation workers.