• Title, Summary, Keyword: 공간감마선량률

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Cross Correlation Analysis of Gamma Exposure Rates and Rainfall, Hours of Saylight, Average Wind Speed in Gangneung Area (강릉 지역 공간 감마선량률과 강수량, 일조시간, 평균풍속 사이 교차 상관성 분석)

  • Cha, Hohwan;Kim, Jaehwa
    • Journal of the Korean Society of Radiology
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    • v.7 no.5
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    • pp.347-352
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    • 2013
  • In this study, we analyze the cross correlation between Gamma exposure rates and Rainfall, Hours of daylight, Average wind speed using cross-correlation coefficient ${\rho}_{DCCA}$ and DCCA cross-correlation coefficient(DCCA ${\rho}$) method. Our data are measured simultaneous in Gangneung regional. First, we find the ${\rho}_{DCCA}$ between Gamma exposure rates and Rainfall is Day(3~7days) 0.57~0.48, Month(30days) 0.39, Season(90days) 0.34, Year(360days) 0.26, between Gamma exposure rates and Hours of daylight is Day -0.20~-0.23, Month -0.22, Season -0.17, Year -0.13, between Gamma exposure rates and Average wind speed is Day -0.10~-0.12, Month -0.11, Season -0.05, Year -0.05. Second, our finding is cross- correlation between Gamma exposure rates and Rainfall, is no cross-correlation between Gamma exposure rates and Hours of daylight, Average wind speed.

Time Series Analysis of Gamma exposure rates in Gangneung Area (강릉 지역 공간 감마선량률의 시계열 분석)

  • Cha, Hohwan;Kim, Jaehwa
    • Journal of the Korean Society of Radiology
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    • v.7 no.1
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    • pp.25-30
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    • 2013
  • In this work, we investigate the statistical properties of gamma exposure rates using well-known analysis methods, such as Autocorrelation Function Analysis(ACF), Rescaled Range Analysis(R/S Analysis), and Detrended Fluctuation Analysis(DFA). Especially, DFA is an important method to reliably detect long-range correlations in non-stationary time series. Our data are measured by Gangneung regional radiation monitoring station over the period of 1998 to 2011. First, we find a crossover indicating two different governing regimes in fluctuations of gamma exposure rates. Within a year, they show a strong long-ranged memory while this property vanishes over the range of time period longer than one year. Second, our finding is very securely supported by a variety of analysis tools. Those tools yield many relevant exponents which satisfies the well known relation between them.

Performance Evaluation of Several Radon Detectors in the Standard Chamber and Dwellings (라돈 표준실과 가옥 내에서 일부 라돈검출기에 대한 성능 평가)

  • Yoon, Seok-Won;Kim, Yong-Jae;Chang, Byung-Uck;Byun, Jong-In;Yun, Ju-Yong
    • Journal of Radiation Protection and Research
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    • v.33 no.4
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    • pp.173-181
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    • 2008
  • To ensure the performance of radon detectors, three passive radon detectors ($RadTrak^{(R)}$, $Radopot^{(R)}$, and $E-PERM^{(R)}$)have been reviewed. The difference ratios of RadTrak and Radopot tested in the radon standard chamber were -13.2% and -6.0%, respectively, which were in good accordance within 20% of the value measured by $AlphaGUARD^{(R)}$. To ensure the performance of the long term measurement, the 3 detectors were installed at the same position of approximately one hundred of dwellings for one year. The correlation curve between RadTrak and Radopot shows good agreement with a correlation coefficient ($R^2$) of 0.91. However, The correlation curve between E-PERM and Radopot shows bad agreement ($R^2$ = 0.021). In addition, the distribution map of annual mean indoor gamma dose rate measured with E-PERM was not in accordance with the distribution map of outdoor gamma dose rate measured by Portable Ion Chamber. According to the results, some requisites for the selection of the radon passive detectors in the large-scale indoor radon survey were discussed.

Dose Rate of Restroom in Facilities using Radioisotope (방사성동위원소 사용시설(내/외) 화장실의 외부선량률)

  • Cho, Yong-Gwi;An, Seong-Min
    • Journal of radiological science and technology
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    • v.39 no.2
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    • pp.237-246
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    • 2016
  • This study is therefore aimed at measuring the surface dose rate and the spatial dose rate in and outside the radionuclide facility in order to ensure safety of the patients, radiation workers and family care-givers in their use of such equipment and to provide a basic framework for further research on radiation protection. The study was conducted at 4 restrooms in and outside the radionuclide facility of a general hospital in Incheon between May 1 and July 31, 2014. During the study period, the spatial contamination dose rate and the surface contamination dose rate before and after radiation use were measured at the 4 places-thyroid therapy room, PET center, gamma camera room, and outpatient department. According to the restroom use survey by hospitals, restrooms in the radionuclide facility were used not only by patients but also by family care-givers and some of radiation workers. The highest cumulative spatial radiation dose rate was 8.86 mSv/hr at camera room restroom, followed by 7.31 mSv/hr at radioactive iodine therapy room restroom, 2.29 mSv/hr at PET center restroom, and 0.26 mSv/hr at outpatient department restroom, respectively. The surface radiation dose rate measured before and after radiation use was the highest at toilets, which are in direct contact with patient's excretion, followed by the center and the entrance of restrooms. Unsealed radioactive sources used in nuclear medicine are relatively safe due to short half lives and low energy. A patient who received those radioactive sources, however, may become a mobile radioactive source and contaminate areas the patient contacts-camera room, sedation room, and restroom-through secretion and excretion. Therefore, patients administered radionuclides should be advised to drink sufficient amounts of water to efficiently minimize radiation exposure to others by reducing the biological half-life, and members of the public-family care-givers, pregnant women, and children-be as far away from the patients until the dose remains below the permitted dose limit.

Measurement of Apron Shielding Rate for X-ray and Gamma-ray (X선 및 감마선에 대한 apron의 차폐율 측정)

  • Park, Myeong-Hwan;Kwon, Deok-Moon
    • Journal of radiological science and technology
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    • v.30 no.3
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    • pp.245-250
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    • 2007
  • This research measured the shielding rates of apron 0.25 and 0.5 mmPb for X-ray energy in diagnosis radiation system and gamma-ray energy of $^{99m}Tc$-MDP and $^{18}F$-FDG. X-ray energies were measured on effective energy of $26.2{\sim}45.6\;keV$ when additional filtering plate of 0, 2 mmAl is used within the range of tube voltage $40{\sim}120\;kVp$, and at this time, apron 0.5 mmPb has shown about 5.5% of increase in its shielding rate over 0.25 mmPb at the highest quality. Besides, the aprons of the two types have shown high shielding rate of over 90% for direct X-ray and spatial dose rate. And, in case 0.25 and 0.5 mmPb aprons were used at 140keV of $^{99m}Tc$-MDP, the shielding effects were between 30 and 53%, and at high energy of 511 keV, $^{18}F$-FDG, the shielding effects of apron, $1.3{\sim}3.6%$, were very small.

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Evaluation of Radiation Exposure to Residents by Naturally Residing Radionuclides in the Soil of Korea (한국토양 내 천연 방사성핵종에 의한 거주민의 방사선피폭평가)

  • Kim, Jung-Hoon;Kim, Ah-Reum;Ko, Seong-Jin;Whang, Joo-Ho
    • Journal of radiological science and technology
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    • v.32 no.2
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    • pp.219-224
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    • 2009
  • We investigated the amounts of radiation exposure from $^{238}U$, $^{232}Th$, and $^{40}K$ which are three major radionuclides naturally residing in soil of the Korean peninsula. The experimental results showed that the concentrations of the radionuclides were 15.77$\pm$7.27, 290.05$\pm$73.92 and 750.30$\pm$165.38 Bq/kg respectively. The absorbed dose rate based on the measured concentrations was 213.76$\pm$46.37 nGy/hr, while the spatial gamma absorbed dose rate measured in the same region was 123.90$\pm$19.18 nGy/hr. The effective dose rate was 0.26 mSv/yr, which is significantly higher than the world average effective dose rate 0.07 mSv/yr provided by the UNSCEAR.

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Determinations of the Exposure Rate Using a NaI(Tl) Detector of the Environmental Radiation Monitor (환경방사선감시기의 NaI(Tl) 검출기를 이용한 조사선량률 결정방법)

  • Ji, Young-Yong;Lee, Wanno;Choi, Sang-Do;Chung, Kun Ho;Kang, Mun Ja;Choi, Geun-Sik
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.11 no.3
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    • pp.245-251
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    • 2013
  • The energy band and the G-factor method were compared to determine the exposure rate from the measured spectrum using a NaI(Tl) scintillation detector. First, G-factors of a 3"${\Phi}X3$" NaI(Tl) detector mounted to a EFRD 3300, which means the environmental radiation monitor, in Korea Atomic Energy Research Institute (KAERI) were calculated for several directions of incident photons through the MCNP modeling, and the optimum G-factor applicable to that monitor was then determined by comparing the results both the energy band method and the G-factor method. The results for these spectrometric determinations were also compared with the dose rate from a HPIC radiation monitor around a EFRD 3300. The measured value at the EFRD 3300 based on a 3"${\Phi}X3$" NaI(Tl) detector was $7.7{\mu}R/h$ and its difference was shown about $3{\mu}R/h$, when compared with the results from a HPIC radiation moditor. Since a HPIC is known to be able to measure cosmic rays with the relatively high energy, the difference between them was caused by cosmic rays which were not detected in a 3"${\Phi}X3$" NaI(Tl) detector.