• Journal of radiological science and technology
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• v.45 no.1
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• pp.49-55
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• 2022

This study is to develop a mobile type environmental radiation measurement system for emergency response or environmental radiation monitoring of local governments near nuclear facilities. A mobile radiation measurement system can monitor radiation by field beyond the spatial constraints of a fixed environmental radiation monitor. If installed in local government infrastructure such as public transportation, environmental radiation can be monitored without additional manpower and measurement work. In addition, it is designed to enable monitoring and measurement of radiation from low to high doses as well as the environment in preparation for radioactive disasters such as nuclear power plant accidents. It is expected that this system will be utilized not only in normal times but also in the event of a radiation accident to improve the disaster prevention capabilities of local governments.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.53-62
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• 2006

Since the direct normal radiation and clear day are a main factor for designing any solar thermal and photovoltaic concentrating system, it is necessary to evaluate its characteristics all over the country. The work presented here are the investigation of direct normal radiation and clear day in Korea. The data utilized in the investigation consist of direct normal radiation collected for 14 years('90. 12${\sim}$2004. 12) and clear-day collected for 23 years($1982{\sim}2004$) at measuring stations across the country. The analysis shows that the annual-average daily direct normal radiation is 5.4 kWh/m2 and the annual-average total clear-day is 92.7 days in Korea. We also constructed the contour map of direct normal radiation and clear-day in Korea by interpolating actually measured data across the country.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1807-1816
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• 2020

In this work, a Gaussian Process (Kriging) approach is proposed to provide efficient dose mapping for complex radiation fields using limited number of responses. Given a few response measurements (or simulation data points), the proposed approach can help the analyst in completing a map of the radiation dose field with a 95% confidence interval, efficiently. Two case studies are used to validate the proposed approach. The First case study is based on experimental dose measurements to build the dose map in a radiation field induced by a D-D neutron generator. The second, is a simulation case study where the proposed approach is used to mimic Monte Carlo dose predictions in the radiation field using a limited number of MCNP simulations. Given the low computational cost of constructing Gaussian Process (GP) models, results indicate that the GP model can reasonably map the dose in the radiation field given a limited number of data measurements. Both case studies are performed on the nuclear engineering radiation laboratories at the University of Sharjah.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.4
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• pp.511-521
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• 2022

Decommissioning of nuclear power plants generates a large amount of radioactive waste in a short period. Moreover, Radioactive waste has various forms including a large volumes of metal, concrete, and solid waste. The disposal of decommissioning waste using 200 L drums is inefficient in terms of economics, work efficiency, and radiation safety. Therefore, The Korea Radioactive Waste Agency is developing large containers for the packaging, transportation, and disposal of decommissioning waste. Assessing disposability considering the characteristics of the radioactive waste and facility, convenience of operation, and safety of workers is necessary. In this study, the exposure dose rate of workers during the disposal of new containers was evaluated using Monte Carlo N-Particle Transport code. Six normal and four abnormal scenarios were derived for the assessment of the dose rate in a near surface disposal facility operation. The results showed that the calculated dose rates in all normal scenarios were lower than the direct exposure dose limitation of workers in the safety analysis report. In abnormal scenarios, the work hours with dose rates below 20 mSv·y^-1 were calculated. The results of this study will be useful in establishing the optimal radiation work conditions.

• Journal of the Korean Solar Energy Society
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• v.30 no.3
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• pp.1-9
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• 2010

Since the horizontal global radiation and cloud cover are a main factor for designing any solar photovoltaic system, it is necessary to evaluate its characteristics all over the country. The work presented here are the investigation of horizontal global radiation and cloud cover in Korea. The data utilized in the investigation consist of horizontal global radiation and cloud cover collected for 27 years(1982. 12~2008. 12) at measuring stations across the country. The analysis shows that the annual-average daily horizontal global radiation is $3.61\;kWh/m^2$ and the annual-average daily cloud cover is 5.1 in Korea. We also constructed the contour map of cloud cover in Korea by interpolating actually measured data across the country.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.969-973
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• 2013

To simulate the effect of high dose-rate radiation on semiconductor devices, device modeling work has been performed especially in the area of photo-current generation by a PIN diode. The resultant analytical values were compared with experimental ones that were specially designed and performed to benchmark the simulation results. Initial results showed 27.85% error between the simulation and the experiment. The error can be further reduced by improvement both in simulation and in related experiments. The developed technique from the study can be applicable to radiation dosimetry and to analysis on the radiation effects in electronics.

• Nuclear Engineering and Technology
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• v.38 no.3
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• pp.225-230
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• 2006

With the advent of inexpensive computing power over the past two decades, applications of Monte Carlo radiation transport techniques have proliferated dramatically. At Los Alamos, the Monte Carlo codes MCNP5 and MCNPX are used routinely on personal computer platforms for radiation shielding analysis and dosimetry calculations. These codes feature a rich palette of variance reduction (VR) techniques. The motivation of VR is to exchange user efficiency for computational efficiency. It has been said that a few hours of user time often reduces computational time by several orders of magnitude. Unfortunately, user time can stretch into the many hours as most VR techniques require significant user experience and intervention for proper optimization. It is the purpose of this paper to outline VR strategies, tested in practice, optimized for several common radiation shielding tasks, with the hope of reducing user setup time for similar problems. A strategy is defined in this context to mean a collection of MCNP radiation transport physics options and VR techniques that work synergistically to optimize a particular shielding task. Examples are offered in the areas of source definition, skyshine, streaming, and transmission.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.124-129
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• 2011

Since the horizontal global radiation and cloud cover are a main factor for designing any solar energy system, it is necessary to evaluate its characteristics all over the country. The work presented here are the investigation of horizontal global radiation and cloud cover in Korea. The data utilized in the investigation consist of horizontal global radiation and cloud cover collected for 27 years(1982.12~2008.12) at measuring stations across the country. The analysis shows that the annual-average daily horizontal global radiation is $3.61kWh/m^2$ and the annual-average daily cloud cover is 5.1 in Korea. We also constructed the contour map of cloud cover in Korea by interpolating actually measured data across the country.

• Radiation Oncology Journal
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• v.3 no.1
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• pp.65-68
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• 1985

Primary lymphoid tumors of orbit are rare. Sometimes they pose difficulty in differentiating malignant non-Hodgkin's lymphoma of the orbit from benign lymphoid hyperplasia or pseudotumor of the orbit by growth characteristics and histologic examination of a biopsy specimen. Consequently, systemic work-up for staging of the disease before the initiation of treatment is essential. All lymphoid tumors of the orbit are radiosensitive and the response to radiotherapy is rapid and complete. Radiation dose for permanent control varies from 2,400 to 4,500rads in $2.5\~4$ weeks depending on extent and location of the disease. A case of localized lymphoma of the orbit was treated with radiotherapy. For the following 15 months, the patient was clinically free of disease without any evidence of side effects of radiation treatment.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.285-294
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• 2023

Autonomous radiation source detection has long been studied for radiation emergencies. Compared to conventional data-driven or path planning methods, deep reinforcement learning shows a strong capacity in source detection while still lacking the generalized ability to the geometry in unknown environments. In this work, the detection task is decomposed into two subtasks: exploration and localization. A hierarchical control policy (HC) is proposed to perform the subtasks at different stages. The low-level controller learns how to execute the individual subtasks by deep reinforcement learning, and the high-level controller determines which subtasks should be executed at the current stage. In experimental tests under different geometrical conditions, HC achieves the best performance among the autonomous decision policies. The robustness and generalized ability of the hierarchy have been demonstrated.