• Nuclear Engineering and Technology
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• v.45 no.6
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• pp.745-752
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• 2013

For thermo-fluid and safety analyses of a High Temperature Gas-cooled Reactor (HTGR), intensive efforts are in progress in the developments of the GAMMA+ code of Korea Atomic Energy Research Institute (KAERI) and the AGREE code of the University of Michigan (U of M). One of the important requirements for GAMMA+ and AGREE is an accurate modeling capability of a bypass flow in a prismatic core. Recently, a series of air experiments were performed at Seoul National University (SNU) in order to understand bypass flow behavior and generate an experimental database for the validation of computer codes. The main objective of the present work is to validate the GAMMA+ and AGREE codes using the experimental data published by SNU. The numerical results of the two codes were compared with the measured data. A good agreement was found between the calculations and the measurement. It was concluded that GAMMA+ and AGREE can reliably simulate the bypass flow behavior in a prismatic core.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.4
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• pp.353-363
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• 2006

In order to evaluate the potential radiological risks for the reuse of the site after decommissioning of nuclear facilities, a mathematical model was developed and materialized into the Microsoft $Excel{\circledR}$ spreadsheets frame. A set of input parameter values was proposed, which is useful in the preliminary risk screening step before the detailed evaluation with the site-specific data. It appeared that the screening levels calculated by the present model was agreed with the derived concentration guideline limits resulted from RESRAD Ver.6.2 and the German dose criteria for releasing a nuclear site from regulatory control.

• Nuclear Engineering and Technology
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• v.50 no.5
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• pp.806-813
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• 2018

$^{222}Rn$ exists in nature in the form of a rare radioactive gas. In terms of environmental radiation, issues regarding $^{222}Rn$ have persisted because of its radiological hazardousness. Ulju County is one of the regions of Ulsan metropolitan city, with a population of 227,699. Ulju County has the highest density of industrial complexes in Korea. In this study, $^{222}Rn$ radioactivity concentration was measured and analyzed in 57 schools in Ulju County using 114 passive LR-115 type detectors to secure radiological safety and confirm basic information for reduction of resident exposure to $^{222}Rn$. The effective dose of $^{222}Rn$ was assessed to find the actual risk of the concentration surveyed in schools to human beings. The dose depended on four factors: subjects, $^{222}Rn$ concentration, dose coefficient, and time. The individuals subjected to dose estimation were classified into three types: students, teachers, and office workers. The subjects had different dwelling locations and times. The findings demonstrate that the radiological hazard to students and workers at schools in Ulju County owing to $^{222}Rn$ is negligible in terms of $^{222}Rn$ activity recommendation level.

• Journal of radiological science and technology
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• v.41 no.6
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• pp.603-610
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• 2018

This study examined the following: accuracy of the exposure conditions in the inverter device and three-phase device; output waveform over the exposure conditions; and average and standard deviation of the output waveform. After assessing whether the dose corresponding to the theoretical dose was presented, the following conclusions were obtained: 1. The accuracy of the tube voltage(kVp) and tube current(mA) exposure time(sec) was within the tolerable level prescribed in Korea's Safety Management Standards. In the error, Inverter device was large the tube voltage and exposure time, the three-phase device was large the tube current. 2. In terms of the output waveform of the exposure conditions and the average and standard deviation of the output waveform, the higher tube voltage and larger tube current resulted in greater standard deviation in pulsation. Moreover, the standard deviation of pulsation was shown to be greater in the inverter device than the three-phase device; there was also greater standard deviation in the inverter device considering the exposure time. 3. Regarding the exposure conditions over the output dose, all linearity showed the coefficient of variation which had an allowable limit of error within 0.05. Although the output dose ratio for the inverter device was 1.00~1.10 times no difference that of the three-phase device, there was almost no difference in dose ratio between the tube currents.

• Progress in Medical Physics
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• v.29 no.4
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• pp.115-122
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• 2018

Although the current internationally recommended standard for the use factor (U) applied to CyberKnife is 0.05 (5%), the CyberKnife shielding standard is applied more stringently. This study, based on clinical data, was aimed at examining the appropriateness of existing shielding guidelines. Sixty patients treated with G4 CyberKnife were selected. The patients were divided into two groups, according to whether they underwent skull or spine tracking. Based on the results, the use factors for each wall ranged from 0.028 (2.8%) to 0.031 (3.1%) for the intracranial treatment and 0.020 (2.0%) to 0.022 (2.2%) for the body treatment. Excessive barrier thickness resulted in inefficient use of space and higher cost to the institutions. Furthermore, because the use factor is influenced by the position of the robot, the use factor determined based on the clinical data of this study would facilitate more reasonable treatment room design.

• Journal of radiological science and technology
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• v.47 no.1
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• pp.13-19
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• 2024

Control of scattered radiation is one of very important factors in the use of medical radiation. In general X-ray exam, the causes, measurement methods, and the kind of detectors of scattered rays within the radiation area are diverse. In this study, the dose of scattered ray was measured by changing the thickness of the polycarbonate phantom and the tube voltage. As a result of measurement of scattered radiation, the results show that the scattered dose significantly(p<.05) increased with growing of thickness of phantom in the tube voltage 40, 50 and 60 kVp(F(p)<.05, R²>64%). As tube voltage increased at all phantom thicknesses, the scattered dose also significantly(p<.05) increased(F(p)<.05, R²>69%). In cases where a significant correlation was shown, the coefficient of determination of more than 60% was shown in regression analysis. The results of this study can be used as data on scattered radiation dose according to the tube voltage and the object thickness in general X-ray imaging exam.

• Journal of radiological science and technology
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• v.30 no.4
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• pp.313-320
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• 2007

There are the Medical Radiation Health and Safety Act(the Patient Radiation Health and Safety Act, the Radiologic Technologist Act), the Medical Laboratory Technologist Act, the Physical Therapy Practice Act, and the Dental Hygienist Act, etc in America. However, Korea has only one Act for a medical radiologic technologist(including radiation therapy technologist, nuclear medicine technologist), medical laboratory technologist, physical therapist, occupational therapy examiner, dental hygienist, and so on. It is the Medical Technologist Act. Therefore, the Medical Radiation Health and Safety Act for a radiologic technologist(including radiation therapy technologist, nuclear medicine technologist) has to be enacted independently in Korea. It is the purpose of this Act to provide for the appropriate certification of persons using radioactive materials, equipment emitting ionizing radiation on humans or performing medical imaging for diagnostic and therapeutic purposes. In Korea, the radiologic technologist is a "fusion technologist" who is a person other than a licensed practitioner as a radiographer, radiation therapist, nuclear medicine technologist, computed tomography technologist, magnetic resonance technologist, mammographer, sonographer, medical dosimetrist, quality management technologist, etc. This Act will have some provisions related to the definitions, reserved title, scope of practice, specialized technologist, application for licensure, radiologic technology council, renewal, continuing education, the radiation control advisory commission, etc. This Act will ensure that quality radiation therapy treatments are delivered and that quality diagnostic information is presented for interpretation, which will lead to accurate diagnosis, treatment and cure. Accurate diagnosis can be provided only when a personnel is properly educated in technique, equipment operation and radiation safety. In the end, this Act will protect the civil right to health. By regulating the personnel responsible for performing those procedures, this Act will mean improved care for patients-higher quality images, improved accuracy, and less exposure to radiation.

• Journal of the Korean Society of Radiology
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• v.6 no.3
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• pp.159-166
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• 2012

The purpose of this study was examine via a survey the knowledge related to radiation safety management (RSM) among radiation workers who operated or used a radiation generator or radioactive isotopes (radioactive isotopes, etc. hereinafter) for industrial use and to systematically analyze the changes in the survey results in order to promote a radiation safety culture for facilities where radiation is used. We administered a questionnaire to 861 radiation workers in the period from August 1 to September 5, 2011. As for the analysis method, a frequency analysis was made for the general characteristics and organization information of survey respondents, while the average and standard deviation were calculated and compared for the knowledge level of the RSM. According to the analysis results, the knowledge level of the RSM was evaluated to be high in all of the radiation workers. In conclusion, it is required to conduct a study on various factors in regards to the RSM among radiation workers. This can contribute to establishing educational programs in a timely manner to increase the awareness of safe and efficient use of radioactive materials and equipments by radiation workers.

• Journal of the Korean Society of Radiology
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• v.11 no.6
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• pp.429-435
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• 2017

In order to increase the therapeutic effect of radiation, there has been an increase in the use of conventional photon therapy. The intensive care unit should pay more attention to the radiation safety evaluation due to the higher energy and the larger facility compared to the existing Photon treatment. These radiation safety evaluations are mainly performed by using Monte Carlo simulation, and the first thing to be done is geometric modeling. The Heavy-ion treatment facility uses synchrotron as the accelerating device, which is difficult to precisely model geometrically and is mostly modeled briefly. This study investigated the effect of simplification and precise implementation of Dipole magnet among the components of synchrotron acceleration device on the radiation safety evaluation. The results show that the simplified geometric model is overestimated with the precisely implemented geometric model. Therefore, it is considered that the radiological safety evaluation results in more reliable results of the precise geometric modeling.

• Journal of radiological science and technology
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• v.29 no.1
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• pp.39-46
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• 2006

The rules and terms are described different meaning, in this results the research is accomplished for preventing practical workers from confusion. Atomic law are kept up modification and development in our situation by the ICRP's recommendation, on the other hand, the rules of diagnosis radiation equipment safety managements are modified partial, then resulted in confusion. The study was comparison between the rules of diagnosis radiation equipment safety management and atomic energy law, and the modification items obtained were as follows. 1. With each other different the terms and units are used. With the exception of special terms for affairs usage, it is needless to say that common term uniformity is standardized. The standardization of rules and guidance have not need to confusion radiological practical workers. 2. The following is omitted. 1) The radiation protection against tile patient and the hospital visitor. 2) Radiation dose limit of the woman patient who is in the process of becoming pregnant. 3) Radiation dose limit of the person who is not regarded as madical madical exposure. 4) The control of the exposure of pregnant of women at work.