• Journal of Radiation Protection and Research
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• v.43 no.2
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• pp.75-84
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• 2018

Background: Gamma-ray spectrometry helps in radiation shielding problems and different applications of radioisotopes. Experimental arrangements including broad beam geometries are widely used. The aim is to investigate and evaluate the ${\gamma}-ray$ spectra via attenuation by environmental materials. Materials and Methods: The photo peak to nominated parts in the ${\gamma}-ray$ spectra and the attenuation coefficients ${\mu}_b/{\rho}$ from broad beam geometries are measured for the materials water, soil, sand and cement at the energies 0.662, 1.25, and 1.332 MeV with a $3{^{\prime}^{\prime}}{\times}3{^{\prime}^{\prime}}$ NaI(Tl) detector. Results and Discussion: The ${\gamma}-ray$ spectra vary according to changes in the effective atomic number $Z_{eff}$ of the attenuator, the photon energy and the solid angle. The peak to total ratios are the most sensitive parts to variations in the experimental conditions and overturn in the region 0.663 MeV to 1.332 MeV. This is indicated as inversion trend. The results are discussed in view of $Z_{eff}$ and the experimental conditions. The intensity build-up is larger at the lower energy and larger scattering angles in agreement with Klein-Nishina formula and other results. The build-up factor B is$${\sim_=}$$1 at high ${\gamma}-energies$ and small scattering angles. Conclusion: The sensitivity to material characteristics decrease gradually from peak: to total, to Compton valley, to Compton plateau ratios. Rigorous collimation is necessary at small energies. Cement, of the largest $Z_{eff}$, is characterized by the maximum broad beam mass attenuation coefficients ${\mu}_b/{\rho}$. The obtained results provide information to decide for the suitable experimental set-up based on aim of the work.

• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.1991-1997
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• 2019

In this manuscript, we present a method for the direct calculation of an ambient dose equivalent (H^* (10)) for the external gamma-ray exposure with an energy range of 40 keV to 2 MeV in an electronic personal dosimeter (EPD). The designed EPD consists of a 3 × 3 ㎟ PIN diode coupled to a 3 × 3 × 3 ㎣ CsI (Tl) scintillator block. The spectrum-to-dose conversion function (G(E)) for estimating H^* (10) was calculated by applying the gradient-descent method based on the Monte-Carlo simulation. The optimal parameters for the G(E) were found and this conversion of the H^* (10) from the gamma spectra was verified by using ²⁴¹Am, ¹³⁷Cs, ²²Na, ⁵⁴Mn, and ⁶⁰Co radioisotopes. Furthermore, gamma spectra and H^* (10) were obtained for an arbitrarily mixed multiple isotope case through Monte-Carlo simulation in order to expand the verification to more general cases. The H^* (10) based on the G(E) function for the gamma spectra was then compared with H^* (10) calculated by simulation. The relative difference of H^* (10) from various single-source spectra was in the range of ±2.89%, and the relative difference of H^* (10) for a multiple isotope case was in the range of ±5.56%.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.22 no.2
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• pp.201-210
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• 1996

Predictive tests for the identification of contact sensitizing chemicals have been developed. We measured the sensitization potential with three predictive tests, the in vitro and the in vivo Local Lymph Node Assay(LLNA), ELISA to detect interferon-gamma(IFN-${\gamma}$) from supernatant and flow cytometry to detect change of cell surface proteins, using draining lymph nodes of mice. BALB/c mice were exposed to various chemicals or vehicles on the ears daily for 3 consecutive days in all experiments. With some exceptions of propyl paraben, neomycin sulfate, the in vivo LLNA was able to detect the sensitizing capacity of test chemicals and was more sensitive than the in vitro LLNA for chemicals used in the present study. In another experiment, contact sensitivity was assessed by the ELISA to detect IFN-Υ from the supernatants of the cultured LNCs after sensitization with chemicals. There was a good correlation between the LLNA and the IFN-Υ production for test chemicals. We also examined the change of cell surface proteins on LNCs after sensitization by flow cytometry for some cell adhesion molecules(ICAM-1, E-cadherine, B7 molecule), T cell markers(CD3, CD4, CD8, T$\alpha$$\beta$,T${\gamma}$$\delta$) and B cell markers(LR1, CD45R, I-Ad). The number of ICAM-1 positive cells and B cells in LNCs were increased after sensitization with DNCB, TNCB, isoeugenol and 25%, 50% cinnamic aldehyde compared with that of vehicle as a control. In conclusion, the in vivo LLNA could provide more sensitive screening test for moderate to strong sensitizers and some weak sensitizers including cosmetic raw materials than the in vitro LLNA. The production of IFN-Υ by allergen-activated LNCs might be a values indicators without radioisotopes for the identification of contact allergens. Detection of allergens by testing the increase of ICAM-1 positive cells and B cells in LNCs by flow cytometry might be used as a test method to detect allergens.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1107-1112
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• 2009

The aim of this study is to develop and synthesize $5-HT_{1A}$ receptor imaging agents with WAY-100635 moiety and $^{99m}Tc(CO)_3$ core. WAY-100635 is commonly known as $5-HT_{1A}$ antagonist and its labeled compound ([$^{11}C$] WAY-100635) has been used as effective radioligand for imaging brain $5-HT_{1A}$ receptors with PET(Positron Emission Tomography). However, there are several restrictions in using a radioisotope of C-11 and requires for more effective radioisotopes and ligands. In order to produce a structure most similar to WAY-100635, WAY-100635 derivatives containing a cysteine chelator were designed and confirmed by using in silico (Hyperchem). The novel compounds (7a, 7b, 7c) were prepared in five or 7 steps with yields of 16%, 36% and 42%, respectively and radiolabeled with $[^{99m}Tc(CO)_3(H_2O)_3]^{+}$. The labeling yield was 99% for all the newly synthesized compounds. [$^{99m}Tc(CO)_3$]- WAY-100635 derivatives show a neutral charge which were confirmed by paper electrophoresis.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.627-632
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• 2007

A fundamental study on the melt decontamination of metal wastes generated by dismantling the nuclear facility, the melting of metal wastes such as stainless steel and carbon steel have been carried out to investigate the distribution phenomena of the radioisotopes such as $^{60}Co$ and $^{137}Cs$ into the ingot, slag and dust phases by using the various slag types, slag concentration and basicity in an arc furnace. The $^{60}Co$ remained homogeneously in the ingot phase above 90 % and it was barely present in the slag below 10 %. The effect of the slag composition on the distribution for Co-60 was not considerable, but a basic slag former with high fluidity showed effective. $^{137}Cs$ was completely eliminated from the melt of the stainless steel as well as the carbon steel and distributed to the slag and the dust phase.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.26 no.2
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• pp.165-174
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• 1996

The authors diagnosed a 33 years old female as benign lymphoepithelial lesion after undergoing clinical, radiological and histopathological examinations and the characteristics were as follows : 1. Clinically, the patient complained of painless bilateral swelling of the parotid glands and dryness of the palate. Rheumatoid factor was detected in her serum. 2. Sialograms showed punctate or globular collections of contrast media distributed evenly throughout the parotid glands in so-called 'cherry blossom' or 'leafless fruit-laden tree' appearance. 3. A salivary gland scan showed no uptake of radioisotopes by the parotid glands. 4. At Tl-weighted imaging of PNS MRI, the lesions had the same signal intensity as the rest of the gland. At TI-weighted imaging, the lesions could be seen as high signal intensity 1.3 cm and 2.1 cm in diameter in the left and the right parotid gland respectively. 5. Ultrasonogram showed sonolucent lesions 20×15mm and 17×14mm in size in the lower part of the left parotid gland and another 18×11mm in size in the lower part of the parotid gland as well as many other small sonolucent lesions. 6. Histopathologically, lymphocytic infiltration replacing the normal acini and lymphoid follicles containing germinal centers could be seen. Epimyoepithelial islands were scattered throughout the lesion and benign lymphoepithelial cysts were also observed.

• The Korean Journal of Nuclear Medicine
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• v.39 no.1
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• pp.1-8
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• 2005

This paper is described on the development of KOTRON-13 and recent status of PET cyclotron by commercial cyclotron companies. KIRAMS has developed medical cyclotron which is KIRAMS-13. Samyoung Unitech produces KOTRON-13 with transfered technology by KIRAMS. As a part of Regional Cyclotron Installation Protect, KOTRON-13 cyclotrons and $[18F]FDG$ production modules are being installed at regional cyclotron centers in Korea. The medical concern with radiation technology has been growing for the last several years. Early cancer diagnosis through the cyclotron and PET-CT have been brought to public attention by commercial cyclotron models in the world. The new commercial cyclotron models are introduced compact low energy cyclotrons developed by CTI, GE, Sumitomo in recent. It produces different short-lived radioisotopes, such as $[^{18}F],\;[^{11}C],\;[^{13}N]\;and\;[^{15}O]$. For the better reliability acceleration particle is proton only. The characteristics of new model cyclotrons are changed to lower energy corresponding to less 13 MeV. New models have self-shielding and low power consumption. Design criteria for the different types of commercial cyclotrons are described with reference to hospital demands.

• Journal of Radiation Industry
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• v.11 no.1
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• pp.39-45
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• 2017

A cyclotron is a kind of particle accelerator that produces a beam of charged particles for the production of medical, industrial, and research radioisotopes. More than 30 cyclotrons are operated in Korea to produce $^{18}F$, an FDG synthesis at hospitals. A 30-MeV cyclotron was installed at ARTI (Advanced Radiation Technology Institute, KAERI) mainly for research regarding isotope production. In this study, we analyze and estimate the items of risk such as the problems in the main components of the cyclotron, the loss of radioactive materials, the leakage of coolant, and the malfunction of utilities, fires and earthquakes. To estimate the occurrence frequency in an accident risk assessment, five levels, i.e., Almost certain, Likely, Possible, Unlikely, and Rare, are applied. The accident consequence level is classified under four grades based on the annual permissible dose for radiation workers and the public in the nuclear safety law. The analysis of the accident effect is focused on the radioactive contamination caused by radioisotope leakage and radioactive material leakage of a ventilation filter due to a fire. To analyze the risks, Occupation Safety and Health Acts is applied. In addition, action plans against an accident were prepared after a deep discussion among relevant researchers. In this acts, we will search for hazard and introduce the risk assessment for the research 30-MeV cyclotron facilities of ARTI.

• Journal of Radiation Industry
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• v.11 no.1
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• pp.7-11
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• 2017

RI-Biomics is a fusion technology in radiation fields for evaluating in-vivo dynamics such as absorption, distribution, metabolism and excretion (RI-ADME) of new drugs and materials using radioisotopes and quantitative evaluation of their efficacy. RI-Biomics information is being provided by RIBio-Info developed as information system for distributing its information and three requirements for improving RIBio-Info system have been derived through reviewing recent big data trends in this study. Three requirements are defined as resource, technology and manpower, and some reviews for applying big data in RIBio-In system are suggested. Fist, applicable external big data have to be obtained, second, some infrastructures for realizing applying big data to be expanded, and finally, data scientists able to analyze large scale of information to be trained. Therefore, an original technology driven to analyze for atypical and large scale of data can be created and this stated technology can contribute to obtain a basis to create a new value in RI-Biomics field.

• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1263-1268
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• 2018

Three different ice core samples from Antarctica were analyzed to identify activity concentrations of radioactive isotopes. Tracking migration of radioactive isotopes to Antarctica can provide a key clue to understand global environmental changes caused by radiation exposures because the Antarctic ice cores can preserve unique characteristics of various environmental conditions. We are particularly interested in the $^{137}Cs$ nucleus, because it is closely related to radiation exposure from nuclear power plant accidents and nuclear bomb tests. With its half life of $30.17{\pm}0.03$ years, $^{137}Cs$ can also be used to assess the age of sedimentation occurring after around the year 1945. We selected three ice core samples, called Tarn8, Styx27, and H25, from different time periods; the Tarn8 sample is known to be from earlier than ~ 1000 AD, the Styx27 sample is approximately from the year 1945, and the H25 sample is from the year 2012. Radioactive isotope measurements of the ice core samples were performed using a 100% HPGe detector at Cheongpyeong Underground Radiation Laboratory (CURL). We measured the activity of $^{137}Cs$ in the H25 sample to be $0.98{\pm}0.82mBq/kg$. Although the activity has a large uncertainty mainly due to the limited sample quantity, the $^{137}Cs$ isotopes in the Antarctic ice core were measured for the first time in Korea.