• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.76-83
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• 2006

Space radiation environment for COMS is simulated by NASA AP8/AE8, JPL91 and NRL CREME models, respectively for trapped particle, solar proton and cosmic-ray. The radiation effects on electronic devices in communication payload are also estimated by using simulation results. Dose-depth curve and LET spectrum are calculated for estimating total ionizing dose(TID) effect and single event effect(SEE) respectively. Spherical sector method is applied to dose estimation at each position in the units of communication payload to consider shielding effect of platform and housing. Total ionizing dose at each position varies by 8 times through shielding effect under the same external space radiation environment.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.347-350
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• 2004

A space radiation analysis has been used to evaluate an ability of electronic equipment boxes or spacecrafts to endure various radiation effects, so it helps design thicknesses of structure and allocate components to meet the radiation requirements. A comparison study of space radiation dose analysis programs SPENVIS Sectoring Tool (SST) and SIGMA II is conducted through some structure cases, simple sphere shell, box and representative satellite configurations. The results and a discussion of comparison will be given. A general comparison will be shown for understanding those programs. The both programs use the same strategy, solid angle sectoring with ray-tracing method to produce an approximate dose at points in representative simple and complex models of spacecraft structures. Also the particle environment data corresponding to mission specification and radiation transport data are used as input data. But there are distinctions between them. The specification of geometry model and its input scheme, the assignment of dose point and the numbers, the prerequisite programs and ways of representing results will be discussed. SST is a web-based interactive program for sectoring analysis of complex geometries. It may be useful for a preliminary dose assessment with user-friendly interfaces and a package approach. SIGMA II is able to obtain from RSICC (Radiation Safety Information Computational Center) as a FOR-TRAN 77 source code. It may be suitable for either parametric preliminary design or detailed final design, e.g. a manned flight or radiation-sensitive component configuration design. It needs some debugs, recompiling and a tedious work to make geometrical quadric surfaces for actual spacecraft configuration, and has poor documentation. It is recommend to vist RSICC homepage and GEANT4/SSAT homepage.

• Journal of Astronomy and Space Sciences
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• v.18 no.1
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• pp.71-80
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• 2001

The threshold voltage shift observed in TDE (Total Dose Experiment) on board the KITAT-1 is converted into dose (rad($SiO_2$)) using the result of laboratory calibration with Co-60 gamma ray source in KAERI (Korea Atomic Energy Research Institute). Simulation using the NASA radiation model of geomagnetosphere verifies that the dose difference between RADFET1 and RADFET3 observed on KITSAT-1 comes from the difference in shielding thickness at the position of these RADFETs.

• Journal of Photoscience
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• v.9 no.3
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• pp.37-40
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• 2002

Astronauts are constantly exposed to space radiation at a low-dose rate during long-tenn stays in space. Therefore, it is important to determine correctly the biological effects of space radiation on human health. Space radiations contain various kinds of different energy particles, especially high linear energy transfer (LET) particles. Therefore, we have to study the relative biological effectiveness (RBE) of space radiation under microgravity environment which may change RBE from a stress for cells. Furthermore, the research about space radiation might give us useful information about birth and evolution of life on the earth. We also can realize the importance of preventing the ozone layer from depletion by use of exposure equipment to sunlight at International Space Station (ISS).

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.367-373
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• 2023

Aircrews and passengers are exposed to radiation from cosmic rays and secondary scattered rays generated by reactions with air or aircraft. For aircrews, radiation safety management is based on the exposure dose calculated using a space-weather environment simulation. However, the exposure dose varies depending on solar activity, altitude, flight path, etc., so measuring by route is more suggestive than the calculation. In this study, we developed an instrument to measure the cosmic radiation dose using a general-purpose Si sensor and a multichannel analyzer. The dose calculation applied the algorithm of CRaTER (Cosmic Ray Telescope for the Effects of Radiation), a space radiation measuring device of NASA. Energy and dose calibration was performed with Cs-137 662 keV gamma rays at a standard calibration facility, and good dose rate dependence was confirmed in the experimental range. Using the instrument, the dose was directly measured on the international line between Dubai and Incheon in May 2023, and it was similar to the result calculated by KREAM (Korean Radiation Exposure Assessment Model for Aviation Route Dose) within 12%. It was confirmed that the dose increased as the altitude and latitude increased, consistent with the calculation results by KREAM. Some limitations require more verification experiments. However, we confirmed it has sufficient utilization potential as a cost-effective measuring instrument for monitoring exposure dose inside or on personal aircraft.

• ETRI Journal
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• v.27 no.4
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• pp.449-452
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• 2005

The electrical characteristics of solid state devices such as the bipolar junction transistor (BJT), metal-oxide semiconductor field-effect transistor (MOSFET), and other active devices are altered by impinging photon radiation and temperature in the space environment. In this paper, the threshold voltage, the breakdown voltage, and the on-resistance for two kinds of MOSFETs (200 V and 100 V of $V_{DSS}$) are tested for ${\gamma}-irradiation$ and compared with the electrical specifications under the pre- and post-irradiation low dose rates of 4.97 and 9.55 rad/s as well as at a maximum total dose of 30 krad. In our experiment, the ${\gamma}-radiation$ facility using a low dose, available at Korea Atomic Energy Research Institute (KAERI), has been applied on two commercially available International Rectifier (IR) products, IRFP250 and IRF540.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.174-180
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• 2015

There are currently many research papers on the knowledge, perceptions and actions of radiation-related staff, but hardly any papers on radiation major students in college who are to be staff members of radiation related jobs in the future. It is of course important to understand the perceptions of staff working on the lines and change their knowledge and perceptions, but in the long term it seems more efficient to understand those who are in the stage of being educated to be staff members-their knowledge and perception of radiation so that ultimately they can attain the right kind of understanding. Therefore the aim of this study is to grasp the pre-radiation staff's basic concept of radiation and space dose, their understanding of radiation safety based on this, and whether there is a change in their perception before and after the space dose measurement experiment; in the end this is to see if the space dose measurement experiment is effective in changing perception on radiation safety. This study took as its subject 64 students majoring radiation in college, I.e. pre-radiation staff members, and gauged their basic conceptualization of radiation, understanding of space dose, and understanding of radiation safety; in the X-ray room within the department the students were asked to measure space dose for themselves, so as to see whether there was a change in their understanding of radiation safety before and after the experiment, according to their understanding of the basic concept of radiation and of space dose. As a result of the space dose measurement experiment, students' increased basic knowledge of concept of radiation and understanding of the dangers of space dose were noteworthy, and accordingly their understanding of radiation safety became stricter and more conservative. In spite of this, their work ethic stayed in the lead of their understanding of radiation safety; this implies the need of a more departmentalized safety education program. Therefore instead of safety education that simply uses visual-audial material in a kind of lecture, I suggest here that there be a more experiential safety education program that enables learners to try out space dose measurement experiments for themselves, a work ethic education that aims for a conventional point of view towards radiation safety as well as a stern attitude.

• Bulletin of the Korean Space Science Society
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• 2005.04a
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• pp.143-147
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• 2005

This paper describes the analysis of radiation environment and effects. TID(Total ionizing Dose) and SEE(Single Event Effects) analysis are implemented. The HAUSAT-2 is a 25kg class nanosatellite which is operated at sun-synchronous orbit at an altitude 650km. Trapped proton and Electron, Solar Proton, Galactic Cosmic Ray models are considered to HAUSAT-2 radiation environment model. Total Dose-depth curve provides TID degree and components are verified by DMBP method and Sectoring analysis. SEE are analysed with Radiation Test Report. Existing Radiation Test Reports are use to SEE analysis of HAUSAT-2.

• Journal of radiological science and technology
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• v.29 no.1
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• pp.21-28
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• 2006

I made inquires about mammographic equipments and circumstances of mammography rooms in the 64 medical facilities in areas of Seoul and Kyong Gi Do. Moreover I had experments about exposure dose with patients and radiologic technologists. so there is the data indicated follows. 1. There are inclined to improve in quality and function of mammographic equipments, it has been proven that s/f system exchanged to DR system. 2. It is certain that the number of examinations are becoming increasingly significant. 3. The Space Scattered Dose of mammography rooms are much more larger than portable equipments. 4. I worry about the affection of expose dose about Space Scattered Dose of mammography room. 5. There is need of study how to cope with the situation about increasing exposure dose of radiologic technologists in small space and numeruous number of examinations.

• Journal of Radiation Protection and Research
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• v.30 no.1
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• pp.17-25
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• 2005

Since the safety of nuclear power plant has been becoming a big social issue the exposure dose of radiation for workers has been one of the important factors concerning the safety problem. The existing calculation methods of radiation dose used in the planning of radiation work assume that dose rate does not depend on the location within a work space thus the variation of exposure dose by different work path is not considered. In this study, a modified numerical method was presented to estimate the exposure dose during radiation work in radwaste storage considering the effects of the distance between a worker and sources. And a new numerical algorithm was suggested to search the optimal work path minimizing the exposure dose in pre-defined work space with given radiation sources. Finally, a virtual work simulation program was developed to visualize the exposure dose of radiation doting radiation works in radwaste storage and provide the capability of simulation for work planning. As a numerical example, a test radiation work was simulated under given space and two radiation sources, and the suggested optimal work path was compared with three predefined work paths. The optimal work path obtained in the study could reduce the exposure dose for the given test work. Based on the results, tile developed numerical method and simulation program could be useful tools in the planning of radiation work.