• Journal of Radiation Protection and Research
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• v.6 no.1
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• pp.25-30
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• 1981

A measurement has been made for the radioactivities (or concentrations) of radon daughters, i.e., RaA, RaB and RaC in airborne dust by means of single filtering method. This is to evaluate the radioactivities in terms of Ci or WL (working level) from gross alpha counts measured in the selected-time intervals after an air sample is taken from a membrane filter paper with a mean pore size of $0.8{\mu}m$. This work involves determinations of standard deviation in radioactivities, radioactive equilibrium factor and ratio. It appears that a concentration of total radon daughters is $0.30{\sim}2.36pCi/l\;or\;0.89{\times}10^{-3}{\sim}6.57{\times}10^{-3}WL$, depending on the sampling time. Generally the highest concentration was observed around nine o'clock in a day while the lowest value was obtained around seventeen o'clock. Standard deviations based on counting statistics of RaA's, RaB's and RaC's concentrations are ${\pm}57.75%,\;{\pm}22.32%\;and\;{\pm}31.29%$, respectively. It is revealed that the radioactive equilibrium factor is 0.322 while the radioactive equilibrium ratio is of pattern $C_1>C_2>C_3$ in general. Here $C_1,\;C_2\;and\;C_3$ stand for concentrations of RaA,RaB and RaC, respectively.

• The Journal of Engineering Geology
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• v.26 no.2
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• pp.261-276
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• 2016

The occurrence of natural radioactive materials such as uranium and radon-222 in groundwater was examined with hydrogeochemistry and geology at ○○ village in the Yongin area. Two rounds of 19 groundwater and 5 surface water sampling were collected for analysis. The range of pH value in groundwaters was 5.81 to 7.79 and the geochemical types of the groundwater were mostly Ca(Na)-HCO₃ and Ca(Na)-NO₃(Cl)-HCO₃. Uranium and radon-222 concentrations in the groundwater ranged from 0.06 to 411 μg/L and from 5.56 to 903 Bq/L, respectively. Two deep groundwaters used as common potable well-water sources exceeded the maximum contaminant levels of the uranium and radon-222 proposed by the United States Environmental Protection Agency (US EPA). Three groundwater samples from residential areas contained unsuitable levels of uranium, and 12 groundwater samples were unsuitable due to radon-222 concentrations. Radioactive materials in the unsuitable groundwater are naturally occurring in a Jurassic amphibole- and biotite-bearing granitic gneiss. High uranium and radon-222 groundwater concentrations were only observed in two common wells; the others showed no relationship between bedrock geology and groundwater geochemical constituents. With such high concentrations of naturally occurring radioactive materials in groundwater, the affected areas may extend tens of meters for uranium and even farther for radon-222. Therefore, we suggest the radon-222 and the uranium did not originate from the same source. Based on the distribution of radon-222 in the study area, zones of higher radon-222 concentrations may be the result of diffusion through cracks, joint, or faults. Surface radioactivity and uranium concentrations in the groundwater show a positive relationship, and the impact areas may extend for ~200m beyond the well in the case of wells containing high concentrations of uranium. The highest uranium and thorium concentrations in rock samples were detected in thorite and monazite.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.431-438
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• 2016

Recently, Both rapid economic growth and high-quality native finishing materials demand in buildings such as local infrastructure facilities and cultural facilities have increased along with local quarries. So, increasing local quarries and environmental pollution occurred in quarries get the eyes to damaged area of the surroundings. As an example, carcinogen such as solid formed to fixing asbestos and dust have damaged to local resident. Especially, Radon gas released from asbestos can exist everywhere on earth, released soil and rock as radioactive substances, can be caused lung cancer followed by a smoking. When pollution source to indoor air quality that lacking ventilation rate of the residential building moved in a cycle, human responses such as headache, dizziness, etc. get appear, so on it threatened resident's physical condition. Thus, we need to urgent attention to reduction harmful substance. In the case of radon gas of the pollution source to indoor air quality in housing, it has characteristic that keep on going through half-life released from source, we need to control radon gas source than source removal. We set on vermiculite addition ratio to 10% which has harmful substances adsorption performance, proceed experiment to basalt waste rock addition ratio 50, 60, 70, 80(%). The result of an experiment, based on 'KS F 4035, precast terrazzo', we can be obtainable in the best terrazzo at basalt waste rock addition ratio 70%.

• The Journal of the Petrological Society of Korea
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• v.17 no.3
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• pp.179-190
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• 2008

The distribution characteristics of some major environmental radionuclides ($^{40}K$, $^{228}Ac$, $^{226}Ra$, $^{222}Rn$) and U in rocks, soils and soil gas were studied at Geumjeong-Gu, Busan, Korea. The activities of radionuclides in granitic rocks are decreased in the odor of $^{40}K$>thorium decay series>uranium decay series. This reveals that Th was relatively more enriched in granitic rocks than U. The U content and activity of $^{226}Ra$ and $^{228}Ac$, however, don't reflect the fractionation sequence of granitic rocks in the study area. The activities of all these radionuclides and U content in soils are generally higher than in rocks, and their distribution in rocks, soils and soil gas show very low co-relationship. These facts indicate that the activities of radionuclides in soil and soil gas were greatly affected by leaching and adsorption properties of the radionuclides and their parents during weathering and pedogenetic process rather than their concentrations in parent rocks.

• Journal of Radiation Protection and Research
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• v.2 no.1
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• pp.9-16
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• 1977

A simple method has been established for determining RaA, RaB and RaC concentrations in airborne dust. This is to evaluate the concentration from measurement of total alpha activities in three selected-time intervals after an air sample is taken from the membrane filter paper (mean pore size: $0.8{\mu}m$). As a preliminary trial, a time-variation of the concentrations has been determined using the single-filter method at the KAERI site (N. Lat. $37^{\circ}38'$ and E. Long $127^{\circ}15'$), Seoul, Korea. It appears that there is a large variation of the concentrations depending on the sampling time. Generally the highest value was observed in the morning that may coincide with the highest density of atmosphere in a day while the lowest value was obtained around fourteen o'clock.

• The Journal of the Acoustical Society of Korea
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• v.28 no.2
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• pp.141-147
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• 2009

This paper presents a new fast algorithm, rotation-based method (RBM), for the reconstruction of 3 dimensional image for cone beam computerized tomography (CB CT) system. The system used cone beam has less exposure time of radioactivity than fan beam. The Three-Pass Shear Matrices (TPSM) is applied, that has less transcendental functions than the one-pass shear method to decrease a time of calculations in the computer. To evaluate the quality of the 3-D images and the time for the reconstruction of the 3-D images, another 3-D images were reconstructed by the radon transform under the same condition. For the quality of the 3-D images, the images by radon transform was shown little good quality than REM. But for the time for the reconstruction of the 3-D images REM algorithm was 35 times faster than radon transform. This algorithm offered $4{\sim}5$ frames a second. It meant that it will be possible to reconstruct the 3-D dynamic images in real time.

• Analytical Science and Technology
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• v.18 no.1
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• pp.5-12
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• 2005

It has been established that soft error of high precision electronic circuits can be induced by alpha particles emitted from the naturally occurring radioactive impurities such as U, and Th. As the electronic circuits have recently become lower dimension and higher density, these alpha-particle emitting radioactive impurities have to be strictly controlled. The aim of this study is to develop of NAA (Neutron Activation Analysis) and gamma-spectrometry to improve the analytical sensitivity and precision of U and Th. A new NAA method has been established using the HTS (Hydrulic transfer system) irradiation facility which has been used to produce radioisotopes for industries and medicines instead of the PTS (pneumatic transfer system) irradiation facility which has been used in general NAA. When the ultratrace impurities have to be analyzed by NAA, background gamma-ray spectra induced from $^{222}Rn$ and its progenies in air is serious problem. This unstable background has been eliminated or stabilized by the use of a nitrogen purging system. Ultra trace amounts of U (0.1 ng/g) and Th (0.01 ng/g) in high purity silica used for EMC could be analyzed by the use of HTS-NAA and low background gamma-spectrometry.

• Journal of radiological science and technology
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• v.44 no.5
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• pp.489-494
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• 2021

In this study, radioactivity quantitative analysis was performed on radon contained in cigarette, and the effective dose was calculated using the result value to determine the amount of exposure caused by smoking. A total of 5 types of cigarettes were sampled. Cigarette smoke was collected by using activated carbon, and tobacco were measured by homogenizing for quantitative analysis. For each sample, Bi-214 and Pb-214 were subjected to gamma nuclide analysis to observe the uranium-based radioactive material contained in cigarette, and a measurement time of 30,000 seconds was set for the sample based on the results of previous studies. As a result of measuring the radioactivity of tobacco, a maximum of 0.715 Bq/kg was derived, and in the case of cigarette smoke measured using activated carbon, a maximum of 3.652 Bq/kg was derived. Using this measurement, the average effective dose to the lungs is 0.938 mSv/y, and it was found that there is a possibility of receiving exposure up to 1.099 mSv/y depending on the type of tobacco. It was found that the exposure dose due to cigarette occupies a large proportion of the annual effective dose limit for the general public. Therefore, more diverse studies on radioactive substances in cigarette are needed, and measures to monitor and reduce the incidental exposure to radon should be established.

• Journal of the Korea Furniture Society
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• v.22 no.1
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• pp.13-17
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• 2011

Recently, interest in indoor air quality is increasing. Especially, radon radioactivity among the indoor air is a well-known risk factor for lung cancer because of ionizing radiation in the form of ${\alpha}$-particles. This study was carried out to investigate effect of black charcoal and activated carbon for reduction of radon radiation that emitted from building materials. Black charcoal and activated carbon were used as a barrier which was against the infiltration of radon. The source of radon was gypsum board. Two types of charcoal barrier were powder- and board-type with 5 mm, 10 mm thickness respectively. The method for this determination is evaluated radon concentration in chamber. The measurements were performed with radon detector, SARAD3120. Results of this study are as following: Black charcoal and activated carbon confirmed the highly efficient barrier. Radon concentration was reduced from 72% to 85% as compared the control chamber. Radon reduction capability, however, was no difference as barrier's types. Results obtained in ventilation condition, radon concentration shows 5.93 pCi/L on average in the closed condition and shows 2.69 pCi/L in the opened condition.

• Journal of radiological science and technology
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• v.44 no.6
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• pp.671-677
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• 2021

Interest in the everyday hazards of radon has recently increased as such, this study attempted to examine the dangers of radon in spilled groundwater by comparing the radon concentrations of the drained groundwater and tap water used in recirculating systems in Incheon Subway restrooms. At five stations of Incheon Subway Line 1 and three stations of Line 2, drained groundwater is recirculated and used in restrooms for toilet flushing. Stations restroom tap water for hand washing that used as a control and the measured values of each were compared. With the cooperation of Incheon Transportation Corporation, samples of spilled groundwater and tap water were collected sealed to prevent contact with the air, and a DURRIDGE RAD7 was used as the experimental equipment. The collected samples were subjected to radial equilibration for approximately 3.5 h, at which the radon concentration reached its maximum, and then calculated as 10 measurements using the RAD7 underwater radon measurement mode. In all eight stations, the radon concentration in tap water was lower than the recommended amount. However, in an average of 7 out of the eight stations, the radon concentration in the effluent groundwater was 100 times higher than that in tap water. Since high radon concentrations in groundwater runoff can be harmful to humans, and there is no accurate standard for radon concentrations in domestic water, it is necessary to continuously monitor radon in water and prepare a guidance of recommended values.