• Journal of Radiation Protection and Research
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• v.24 no.2
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• pp.101-108
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• 1999

The influence of the relative humidity, the temperature and the velocity of supply air on evaporation rate has been studied with non-boiling forced evaporation system in order to treat very low level radioactive liquid wastes produced from the decontamination and decommissioning activities. Experimental data on the evaporation rate have been obtained with the divers variables and experimental equation of air velocity was also obtained by the correlation of those data. The decontamination factor of this system was also obtained by the experimental data from a simulated liquid waste containing Cs-137 radio isotope ; $DF=10^4$. Since the commercial system will be operated for the treatment of the very low level radioactive liquid waste produced from decontamination & decommissioning of TRIGA Mark-II&III research reactor, the environmental assessment has been conducted to improve the operational safety. Exposure dose rate for an individual member of general public was assessed, and it showed that it was very lower than individual dose limits. The release of radioactivity of radioisotope material (Cs-137) to the environment was assessed, and result showed that it was $4.637{\times}10^{-14}\;{\mu}Ci/cc$.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.125-129
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• 2016

Background: Patients with differentiated thyroid cancers (DTC) who receive radioactive iodine-131 (RAI) are released from isolation when their dose rate is below the regulatory requirements. The purpose of this study was establish predicting factors for early release from the isolation facility after RAI administration in patients with DTC. Materials and Methods: This was a prospective study which included 96 (58 females and 38 males) patients with DTC who had received RAI from April 2013 till August 2015. The study was duly approved by the ethical committee of the institute. Patients who had complete information of primary tumor size (PTS), serum TSH, stimulated thyroglobulin level [sTg] with antibodies (IU/ml) at the time of RAI treatment were included. All had a normal serum creatinine level. To attain lower effective half-life good hydration and administration of soft laxative were ensured. Dose rate was measured (immediately, 24 h and 36 h) at 1 meter distance from anterior mid trunk and a dose rate <$50{\mu}Sv/h$ was considered as the releasing criterion. At 24 h 50 patients were released while the remaining 46 patients were released at 36 h. A post-ablative whole body scan (PA-WBIS) was performed 5-8 days after RAI ablation in all patients. Results: Patients released after 24 h were significantly younger, had smaller lesions with higher proportion of papillary cancer, lower sTg, lower sTg/TSH ratio and had received a lower dose of RAI as comapred to those who were discharged after 36 h. Serum TSH and gender were not found to have any significant correlation between two cohorts. ROC and multivariate analysis have shown age ${\leq}37years$, PTS ${\leq}3.8cm$, $RAI{\leq}150mCi$, $sTg{\leq}145ng/ml$ and $sTg/TSH{\leq}1.085$ as strong indepedent predictors for early release. Conclusions: We conclude that younger age (${\leq}37years$), smaller tumor size (${\leq}3.8cm$), lower RAI dose (${\leq}150mCi$), lower sTg (${\leq}145ng/ml$) and a lower sTg/TSH ratio (${\leq}1.085$) are significant independent predictors for release at 24 h after RAI treatment in DTC patients. Effective utilization of these factors could help the treating physicians to use limited number of internment facilities with higher throughput, lower cost and lower psychological stress to patients.

• Progress in Medical Physics
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• v.10 no.3
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• pp.159-168
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• 1999

Cardiac disease is one of the leading causes of death in Korea. In quantitative analysis of cardiac function and morphological information by three-dimensional reconstruction of magnetic resonance images, left ventricle provides an important role functionally and physiologically. However, existing procedures mostly rely on the extensive human interaction and are seldom evaluated on clinical applications. In this study, we developed a system which could perform automatic extraction of enpicardial and endocardial contour and analysis of cardiac function to evaluate reliability and stability of each system comparing with the result of ARGUS system offered 1.5T Siemens MRI system and manual method performed by clinicians. For various aspects, we investigated reliability of each system by compared with left ventricular contour, end-diastolic volume (EDV), end-systolic volume (ESV), stock volume (SV), ejection fraction (EF), cardiac output (CO) and wall thickness (WT). When comparing with manual method, extracted results of developed process using minimum error threshold (MET) method that automatically extracts contour from cardiac MR images and ARGUS system were demonstrated as successful rate 90% of the contour extraction. When calculating cardiac function parameters using MET and comparing with using correlation coefficients analysis method, the process extracts endocardial and epicardial contour using MET, values from automatic and ARGUS method agreed with manual values within :t 3% average error. It was successfully demonstrated that automatic method using threshold technique could provide high potential for assessing of each parameters with relatively high reliability compared with manual method. In this study, the method developed in this study could reduce processing time compared with ARGUS and manual method due to a simple threshold technique. This method is useful for diagnosis of cardiac disease, simulating physiological function and amount of blood flow of left ventricle. In addition, this method could be valuable in developing automatic systems in order to apply to other deformable image models.

• Progress in Medical Physics
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• v.27 no.3
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• pp.146-155
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• 2016

As the probability of exposure to radiation increases due to an increase in the use of radioisotopes and radiation generators, the importance of a radiation safety management field is being highlighted. We intend to help radiation workers with exposure management by identifying the degree of radiation exposure and contamination to determine an efficient method of radiation safety management. The personal exposure doses of the radiation workers at the Korea Institute of Radiological & Medical Sciences measured every quarter during a five-year period from Jan. 1, 2011 till Dec. 31, 2015 were analyzed using a TLD (thermoluminescence dosimeter). The spatial dose rates of radiation-controlled areas were measured using a portable radioscope, and the level of surface contamination was measured at weekly intervals using a piece of smear paper and a low background alpha/beta counter. Though the averages of the depth doses and the surface doses in 2012 increased from those in 2011 by about 14%, the averages were shown to have decreased every year after that. The exposure dose of 27 mSv in 2012 increased from that in 2011 in radiopharmaceutical laboratories and, in the case of the spatial dose rate, the rate of decrease in 2012 was shown to be similar to the annual trend of the whole institute. In the case of the surface contamination level, as the remaining radiation-controlled area with the exception of the I-131 treatment ward showed a low value less than $1.0kBq/m^2$, the annual trend of the I-131 treatment ward was shown to be similar to that of the entire institute. In conclusion, continuous attention should be paid to dose monitoring of the radiation-controlled areas where unsealed sources are handled and the workers therein.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.345-351
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• 2020

In this study, a dose assessment was conducted on the exposure dose of thyroid, breast and sexual gland using a personal dosimeter in multiple CT examinations currently being conducted in health examinations. The dose assessment was measured by attaching TLD and EPD to the locations of the thyroid, breast and sexual gland during CT examinations of Brain, Brain + C-S, Brain + Low lung, Brain + L-S among CT items. The generated dose of equipment, CTDI_vol and DLP, was measured. The study found that effective doses were rated 41.7% higher for thyroid TLD in Brain + C-S CT examinations than for the general public, 156% higher for EPD, 10% for breast EPD in Brain + Low Lung CT examinations, 124.4% higher for reproductive TLD and 339.8% higher for Brain + L-S CT examinations. The CTDI_vol and DLP analysis results showed that C-S CTDI_vol values were higher than the diagnostic reference levels at 0.6%, Low Lung CTDI_vol values at 5.7%, DLP values at 11.8% and L-S CTDIvol values at 1.2%. In order to reduce the exposure dose of patients, indiscriminate examination is reduced and dose limit setting is needed in health examination.

• Nuclear Engineering and Technology
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• v.46 no.4
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• pp.547-556
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• 2014

Korea expects a shortage in storage capacity for spent fuels at reactor sites. Therefore, a need for more metal and/or concrete casks for storage systems is anticipated for either the reactor site or away from the reactor for interim storage. For the purpose of interim storage and transportation, a dual purpose metal cask that can load 21 spent fuel assemblies is being developed by Korea Radioactive Waste Management Corporation (KRMC) in Korea. At first the gamma and neutron flux for the design basis fuel were determined assuming in-core environment (the temperature, pressure, etc. of the moderator, boron, cladding, $UO_2$ pellets) in which the design basis fuel is loaded, as input data. The evaluation simulated burnup up to 45,000 MWD/MTU and decay during ten years of cooling using the SAS2H/OGIGEN-S module of the SCALE5.1 system. The results from the source term evaluation were used as input data for the final shielding evaluation utilizing the MCNP Code, which yielded the effective dose rate. The design of the cask is based on the safety requirements for normal storage conditions under 10 CFR Part 72. A radiation shielding analysis of the metal storage cask optimized for loading 21 design basis fuels was performed for two cases; one for a single cask and the other for a $2{\times}10$ cask array. For the single cask, dose rates at the external surface of the metal cask, 1m and 2m away from the cask surface, were evaluated. For the $2{\times}10$ cask array, dose rates at the center point of the array and at the center of the casks' height were evaluated. The results of the shielding analysis for the single cask show that dose rates were considerably higher at the lower side (from the bottom of the cask to the bottom of the neutron shielding) of the cask, at over 2mSv/hr at the external surface of the cask. However, this is not considered to be a significant issue since additional shielding will be installed at the storage facility. The shielding analysis results for the $2{\times}10$ cask array showed exponential decrease with distance off the sources. The controlled area boundary was calculated to be approximately 280m from the array, with a dose rate of 25mrem/yr. Actual dose rates within the controlled area boundary will be lower than 25mrem/yr, due to the decay of radioactivity of spent fuel in storage.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.378-384
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• 2012

In aquatic invertebrates, particularly marine gastropods, organotin compounds induce irreversible sexual abnormality in females, which is termed imposex, at very low concentrations. Organotin compounds are agonists for nuclear receptors such as RXRs and $PPAR{\gamma}$. However, the imposex phenomenon has not been reported to act as an antagonist on estrogen receptors in other species, including vertebrates and invertebrates. In order to gain insights into the antagonistic activity of organotin compounds on estrogen receptors (ERs), we examined the inhibitive effect of these compounds on estradiol-dependent ${\beta}$-galactosidase activity using the yeast two-hybrid detection system consisting of a combination of the human estrogen receptor ($hER{\beta}$) ligand-binding domain and the co-activator steroid receptor co-activator-1 (SRC1). Tributyltin-hydroxide (TBT-OH) and triphenyltin-chlorine (TPT-Cl) exhibited an inhibitive effect on $E_2$-dependent transcriptional activity, similar to antagonistic chemicals such as 4-hydroxytamoxifen (OHT) or ICI 182,780, at a very low concentration of $10^{-14}$ M TBT or $10^{-10}$ M TPT, respectively. The yeast growth and transcriptional activity with transcriptional factor GAL4 did not exhibit any effect at the tested concentration of TBT or TPT. Moreover, the yeast two-hybrid system using the interaction between p53 and the T antigen of SV40 large did not describe any effect at the tested concentration of OHT or ICI 182,780. However, the interaction between p53 and T antigen was inhibited at a TBT or TPT concentration of $10^{-9}$ M, respectively. These results indicate that TBT and TPT act as inhibitors of ER-dependent reporter gene transcriptional activation and of the interaction between $hER{\beta}$ LBD and the co-activator SRC1 in the yeast two-hybrid system. Consequently, our data could partly explain the occurrence of organotin compound-induced imposex on the endocrine system of mammals, including humans.

• KSBB Journal
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• v.10 no.3
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• pp.283-291
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• 1995

The characteristics of aminopeptidase M(ApM) immobilized covalently on Cellufine Formyl and the continuous production of authentic human growth hormone(hGH) from methionyl human growth hormono(met-hGH) using the column reactor packed with immobilized ApM were investigated. Immobilized ApM with the proportion of 2.3mg ApM per 1g Cellufine Formyl gel had the highest met-hGH conversion activity. The optimum pH(7.0) and temperature($55^{\circ}C$) showed no appreciable difference between free and immobilized enzymes and the optimum temperature in continuous operation of the column reactor was also found to be $55^{\circ}C$. Under the conditions at which met-hGH was converted completely to hGH, the yield and productivity were about 77% and 0.8mg hGH/ml$.$h, respectively. In two column reactors of different sizes, met-hGH was converted to hGH with the same conversion rates and hGH yields at the same space velocities. The half-life of the reactor systems at $45^{\circ}C$ and $55^{\circ}C$ were projected from the continuous operations for 90 days to be 225 days and 81 days, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1027-1035
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• 2000

This study was carried out to investigate the treatability of landfill leachate having high concentration of ammonium nitrogen with/without the circulation of media in pilot-scale($48m^3basis$) process. Total nitrogen removal efficiency was relatively increased in the media added process (influent ; $1.230{\sim}2,000mg{\cdot}l^{-1}$, effluent ; $120{\sim}250mg{\cdot}l^{-1}$) compared with the control process. The difference of nitrogen removal efficiency between these processes may be due to that stable growth of nitrifiers attached to the media could be achieved 99.3% of ammonium-nitrogen removal efficiency(without ; 98.2%) and 88.5% of total nitrogen removal efficiency(without ; 85.8%) were shown in media added process, respectively. Also, optimum BOD/ $NH_4{^+}$-N ratio was relatively decreased in the media process compared with the control process. Sludge settleability, on the other hand. was shown better in media added process than in control process. This outstanding sludge settleability in the media added process indicates the compatibility of media(zeolite) to the microorganism and the possibility of using media of biofilm process.

• Journal of Korean society of Dental Hygiene
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• v.4 no.1
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• pp.15-29
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• 2004

The purpose of this study was to understand the relationship among knowledge, attitude, and behavior of dental personnel about the defense against dental radiation according to general features, and help them recognize the importance of defense against dental radiation. A questionnaire survey of 187 dental personnel who were working in 121 medical institutions such as university hospitals, general hospitals, hospitals, clinics, and public health centers in Seoul area was conducted from December 2002 to January 2003. Study findings are as follows: 1. The average knowledge score for the defense of radiation was 9.51(full score=14): By the demographic features, the know level for the defense of radiation was appeared to be different with the occupational category, age, academic background, workplace, year of working, and whether having the education of radiation or not. By questionnaire items, the knowledge for the defense of radiation was high in general, but for the item. 'the average amount of being bombed with radiation according occupations cannot be over 20mSv in a year for prescribed 5 years'. it was 18.7%: and for the item. 'the longer the length between focus and film. the less the amount of skin exposure', it was 40.6%. showing less knowledge for these two items. 2. The average attitude score for the defense of radiation was 64.24 (full score=75): By the demographic features, the attitude score was higher with respondents who were 31-35 years old. 11-15 years of working. and having radiation education. The attitude score by questionnaire items was generally high for all the items. 3. The average behavior score for the defense of radiation was 45.43: (a) By the demographic features, the behavior score for the defense of radiation was appeared to be higher with respondents who were dentists for occupational category, the aged for age, holding higher diploma for academic background, working in the university hospitals for workplace, and having longer occupational career for the year of working. (b) The behavior score for the defense of radiation by questionnaire items was lower than that of the attitude score for all the items. For the item, 'the amount of X-ray radiation is adjusted according to such conditions as patients' age, radiating areas, and kind of films', the score was 4.03; and for the item, 'Must receive the education of safety management of radiation periodically', the score was 1.73 and it was the lowest one. 4. As for the correlation among the knowledge, attitude, and behavior for the defense of radiation, the higher the level of knowledge and attitude, the higher the level of behavior.