• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1516-1523
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• 2003

An inverse radiation analysis is presented for the estimation of the boundary emissivities for an absorbing, emitting, and scattering media with diffusely emitting and reflecting opaque boundaries. The finite-volume method is employed to solve the radiative transfer equation for a two-dimensional irregular geometry. A hybrid genetic algorithm is proposed for improving the efficiency of the genetic algorithm and reducing the effects of genetic parameters on the performance of the genetic algorithm. After verifying the performance of the proposed hybrid genetic algorithm, it is applied to inverse radiation analysis in estimating the wall emissivities in a two-dimensional irregular medium when the measured temperatures are given at only four data positions. The effect of measurement errors on the estimation accuracy is examined.

• Proceedings of the Korean Society of Crop Science Conference
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• 2007.11a
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• pp.228.1-228.1
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• 2007

• Molecular & Cellular Toxicology
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• v.5 no.2
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• pp.165-171
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• 2009

Biomarkers indicating past exposure to radiation have not yet been entirely satisfactory. In this study, we validated several genes reported as radiation response genes, as biomarkers to detect past exposure to radiation in occupationally exposed workers, especially workers in the medical field. A total of 54 radiation workers in hospital were investigated for radiation exposure dose. Their average radiation dose of recent one year was 1.09 mSv ($\pm$1.63) with a 10.63 mSv ($\pm$12.91) cumulative dose. The results of the multiple regression analysis for the various variables indicate that the Hsc70 (P=0.0292) and ORAL (P=0.0045) may be candidate biomarkers for the recent 1 year radiation exposure in radiation workers, whereas AEN (P=0.0334) and PGAMI (P=0.0003) might be for cumulative exposure.

• Korean Journal of Adult Nursing
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• v.28 no.6
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• pp.680-690
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• 2016

Purpose: This study was designed to identify knowledge, attitude, environment, and self-efficacy among perioperative nurses in terms of radiation protection and to describe those factors affecting radiation protection behaviors. Methods: The sample was comprised of 128 perioperative nurses who agreed to participate in this descriptive study. Data were collected from a self-administered questionnaire and were analyzed using the t-test, analysis of variance, Mann-whitney U test, Kruskal-Wallis test, Pearson's correlation, and multiple regression analyses. Results: Radiation protection behaviors were significantly different by participant's gender, length of career as a perioperative nurse, educational level and prior experience with radiation protection education. Radiation protection behaviors were significantly correlated with radiation protection environment and self-efficacy in terms of radiation protection behaviors. In the multiple linear regression models, radiation protection environment and self-efficacy on radiation protection behaviors were statistically significant predictors of radiation protection behaviors, which accounted for 50.3% of variance in dependent variable. Conclusion: This study concluded that radiation protective environment in operating room is important to promote radiation protective behaviors and radiation safety management program to enhance self-efficacy is highly recommended.

• Journal of Radiation Industry
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• v.5 no.1
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• pp.1-5
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• 2011

Since proteomics can be employed to compare changes in the expression levels of many proteins under particular genetic and environmental conditions, using mass spectrometry to establish radiation stimulon, we performed two-dimensional gel electrophoresis and identified E. coli proteins whose expressions are affected by high dose of ionizing radiation. After exposure to 3 kGy, it was found that 6 proteins involved in carbon and energy metabolism were reduced. Although 4 of 7 protein spots showing a significant increase in expression level were neither identified nor classified, uridine phosphorylase (Udp), superoxide dismutase (SodB), and thioredoxin-dependent thiol peroxidase (Bcp) were proven to be up-regulated after irradiation. This suggests that E. coli subjected to high doses of radiation (3 kGy) may operate a defense system that is able to detoxify reactive oxygen species and stimulate the salvage pathway of nucleotide synthesis to replenish damaged DNA.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.7 s.262
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• pp.635-643
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• 2007

An inverse radiation analysis is presented for the estimation of the radiation properties for an absorbing, emitting, and scattering media with diffusely emitting and reflecting opaque boundaries. In this study, a repulsive particle swarm optimization(RPSO) algorithm which is a relatively recent heuristic search method is proposed as an effective method for improving the search efficiency for unknown parameters. To verify the performance of the proposed RPSO algorithm, it is compared with a basic particle swarm optimization(PSO) algorithm and a hybrid genetic algorithm(HGA) for the inverse radiation problem with estimating the various radiation properties in a two-dimensional irregular medium when the measured temperatures are given at only four data positions. A finite-volume method is applied to solve the radiative transfer equation of a direct problem to obtain measured temperatures.

• Journal of Radiation Protection and Research
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• v.34 no.2
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• pp.55-64
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• 2009

In a pressurized heavy water reactor (PHWR), radiation workers who have access to radiation controlled areas submit their urine samples to health physicists periodically; internal radiation exposure is evaluated by the monitoring of these urine samples. Internal radiation exposure at PHWRs accounts for approximately 20 $\sim$ 40% of total radiation exposure; most internal radiation exposure is attributed to tritium. Carbon-14 is not a dominant nuclide in the radiation exposure of workers, but it is one potential nuclide to be necessarily monitored. Carbon-14 is a low energy beta emitter and passes relatively easily into the body of workers by inhalation because its dominant chemical form is radioactive carbon dioxide ($^{14}CO_2$). Most inhaled carbon-14 is rapidly exhaled from the worker's body, but a small amount of carbon-14 remains inside the body and is excreted by urine. In this study, a method for dual analysis of tritium and carbon-14 in urine samples of workers at nuclear power plants is developed and a method for internal dose assessment using its excretion rate result is established. As a result of the developed dual analysis of tritium and carbon-14 in urine samples of radiation workers who entered the high radiation field area at a PHWR, it was found that internal exposure to carbon-14 is unlikely to occur. In addition, through the urine counting results of radiation workers who participated in the open process of steam generators, it was found that the likelihood of internal exposure to either tritium or carbon-14 is extremely low at pressurized water reactors (PWRs).

• Journal of Radiation Protection and Research
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• v.34 no.4
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• pp.176-183
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• 2009

Maintenance on the water chamber of steam generator during outage in nuclear power plants (NPPs) has a likelihood of high radiation exposure to whole body of workers even short time period due to the high radiation exposure rates. In particular, it is expected that hands would receive the highest radiation exposure because of its contact with radiation materials. In this study, characteristic analysis of inhomogeneous radiation fields for contact operations was conducted using thermoluminescent dosimeter (TLD) readouts from the application tests of two-dosimeter algorithm to Korean NPPs in 2004. It is regarded that inhomogeneous radiation fields for contact operations in NPPs are dominated by high energy photons. In addition, field tests for workers who participated in maintenance on the steam generator during outage at Ulchin NPPs in 2009 and pressure tube replacement at Wolsong NPPs in 2009 were conducted to analyze radiation fields and to estimate the extremity dose. As a result, radiation fields were dominated by high energy photons.

• Radiation Oncology Journal
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• v.29 no.3
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• pp.206-213
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• 2011

Purpose: Intensity modulated radiation therapy (IMRT) is a high precision therapy technique that can achieve a conformal dose distribution on a given target. However, organ motion induced by respiration can result in significant dosimetric error. Therefore, this study explores the dosimetric error that result from various patterns of respiration. Materials and Methods: Experiments were designed to deliver a treatment plan made for a real patient to an in-house developed motion phantom. The motion pattern; the amplitude and period as well as inhale-exhale period, could be controlled by in-house developed software. Dose distribution was measured using EDR2 film and analysis was performed by RIT113 software. Three respiratory patterns were generated for the purpose of this study; first the 'even inhale-exhale pattern', second the slightly long exhale pattern (0.35 seconds longer than inhale period) named 'general signal pattern', and third a 'long exhale pattern' (0.7 seconds longer than inhale period). One dimensional dose profile comparisons and gamma index analysis on 2 dimensions were performed. Results: In one-dimensional dose profile comparisons, 5% in the target and 30% dose difference at the boundary were observed in the long exhale pattern. The center of high dose region in the profile was shifted 1 mm to inhale (caudal) direction for the 'even inhale-exhale pattern', 2 mm and 5 mm shifts to exhale (cranial) direction were observed for 'slightly long exhale pattern' and 'long exhale pattern', respectively. The areas of gamma index >1 were 11.88 %, 15.11%, and 24.33% for 'even inhale-exhale pattern', 'general pattern', and 'long exhale pattern', respectively. The long exhale pattern showed largest errors. Conclusion: To reduce the dosimetric error due to respiratory motions, controlling patient's breathing to be closer to even inhaleexhale period is helpful with minimizing the motion amplitude.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.161-165
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• 2016

Background: Radiation accidents having occurred in recent containing the accident in Fukushima nuclear power plants of Japan were resulted to the increase in some public concern, anxiety and confusion for radiation or nuclear safety. The public anxiety for radiation is not being decreased though the announcements done in radiation research institutes in Korea. Therefore, this study aims at providing an effective system for radiation publicity to the public members by the clipping analysis for the radiation articles reported in the media. And, the relation between those radiation issues and the radiation perception to the public members is analyzed. Materials and Methods: The radiation articles reported by them in 2013 and 2014 have been collected, and they are then classified with the article characteristic, field and tendency. Classified articles have been reviewed by dividing as two year. The 210 articles have been compared for their tendencies, characteristics and fields by year reported, and their characteristic comparison by reported year are then reviewed. Results and Discussion: Though the frequency that the radiological accidents have occurred in worldwide is far low compared to the accidental frequencies occurred in the general industrial fields, the radiation perception is being still deteriorated because of its special problem, which is defined as exposure, contamination or radioactivity, about radiation. The basic principles for radiation communication were suggested for preventing some unnecessary misunderstanding due to the variation of understanding for radiation issues. Conclusion: It is necessary to perform a variety of strategies for the publicity in improving the radiation perception, to build a relationship with the press or the media and then to consistently interact with them. Radiation communication must be performed by radiation experts or complete charge department, and must be consistently performed and be taken predictable patterns.