• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.52-58
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• 2004

This work was conducted to provide the reference data of radioactivity in the foodstuffs at a radiological emergency situation in Jeju Island The sampled foodstuffs were agricultural (31), livestock (6), marine (12) and forest products (4), and processed foods (3) consumed by Jeju Islanders. $^{137}Cs$ and $^{40}K$ activities were determined by HPGe r-ray spectromety. The activity ranges of $^{137}Cs$ was ${\sim}650\;mBq/kg$ fresh in the agricultural products, ${\sim}131\;mBq/kg$. fresh in the livestock, ${\sim}834\;mBq/kg$ fresh in the forest, ${\sim}253\;mBq/kg$ fresh in the marine and $32.0{\sim}483\;mBq/kg$. fresh in the processed foods (tea). In case of $^{40}K$ the activity was $16.6{\sim}542\;Bq/kg$. fresh in the agricultural products, $39.1{\sim}294\;Bq/kg$ fresh in the livestock, $85.5{\sim}116\;Bq/kg$ fresh in the forest, $50.1{\sim}657\;Bq/kg$ fresh in the marine, and $33.6{\sim}1,065\;Bq/kg$ fresh in the processed foods (tea). The highest activity of $^{137}Cs$, 834mBq/kg fresh was observed in oak mushroom and $^{40}K$ 1,065 Bq/kg fresh in coffee. Annual effective doses of $^{137}Cs$ and $^{40}K$ by intake of foodstuffs per capita were the following order; agricultural products (66,543 nSv) > livestock products (19,311 nSv) > processed foods (6,648 nSv) > marine products (6,579 nSv) > forest products (860 nSv). Therefore, total annual effective dose was summed 99,941 nSv which is quite low level comparing to the annual effective dose by external exposure, 2,400,000 nSv. The data obtained in this study can be useful for monitoring whether the foodstuffs are contaminated or not at an emergency radiation accident, and showed that the foodstuffs consumed in Jeju are safe in terms of annual effective dose of $^{137}Cs$ and $^{40}K$

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.544-548
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• 2003

The Irradiation test of bar code label tagged on radioactive waste container was done to determine the effect of radiation. Low and medium radioactive waste is that below total activity of 4,000 Bq/g according to the Korean nuclear law. The irradiation amount to radiate bar code label tagged on radioactive waste container was calculated by MCNP-4b computer code. The nuclide such as Co-60 and Cs-137 was assumed to contribute 50% of total activity. Real irradiation amount for bar code label was finally calculated by the dimensions of the container and the bar code label. The Identification of post and the physical deflection of irradiated bar code label was tested by the bar code reader. The coated bar code label was suitable to use on low and medium radioactive waste container.

• Journal of Sensor Science and Technology
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• v.4 no.4
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• pp.1-9
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• 1995

The ${\gamma}$-ray deposition spectra were calculated by Monte Calro method to obtain the scintillation characteristics of the ${\gamma}$-ray for BGO scintillation detector with the spherical shape of 1.25 cm radius. The code used in calculating the ${\gamma}$-ray deposition spectra was made for personal computer with qbasic language. Also the ${\gamma}$-ray energy spectra of $^{22}Na$, $^{137}Cs$ and $^{207}Bi$ were measured with the detector. The energy dependent resolution below 2000 keV for the detector was determined by estimating the standard deviation of the photopeak fitted with gaussian function, and $X^{2}$ fitting using Nardi's empirical formula. The measured spectra of $^{22}Na$ and $^{137}Cs$ were compared with the broadened spectra which were obtained by broadening the calculated ${\gamma}$-ray deposition spectra with the energy dependent resolution. The absolute efficiency and the intrinsic peak efficiency of the detector were obtained by calculating the ${\gamma}$-ray deposition spectrum with the code.

• Journal of Radiation Protection and Research
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• v.26 no.4
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• pp.441-445
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• 2001

In this work we investigated distribution of the natural and artificial radioactive nuclides and level of the regional background in soil in Busan. For 45 points, the environmental radioactivity concentration of Busan surface soil is $14.38{\sim}57.03\;(mean\;:\;33.95)\;Bq{\cdot}kg^{-1}$ for $^{226}Ra,\;2.41{\sim}86.58\;(mean\;:\;51.08)\;Bq{\cdot}kg^{-1}$ for $^{228}Ra,\;223.64{\sim}1332.30\;(mean\;668.51)\;Bq{\cdot}kg^{-1}$ for $^{40}K$ and $<0.33{\sim}33.37\;(mean:13.74) Bq{\cdot}kg^{-1}$ for $^{137}Cs$. Also, in order to investigate vertical distribution for radioactivity, we examined radioactive concentration with mountain height. But there was no correlation between radiaoactivity distribution and mountain height. The $^{226}Ra/^{228}Ra$ and $^{226}Ra/^{40}K$ concentration ratios were $0.68{\pm}19 %$ and $0.06{\pm}34%$, respectively.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.51-57
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• 2002

An electronic personal dosimeter(EPD) with hybrid type preamplifier adopting a semiconductor detector as a radiation detector has been developed, manufactured and test-evaluated. The radiation detection characteristics of this EPD has been performance-tested by using a reference photon radiation field. After several test-irradiations to a $^{137}Cs$ gamma radiation source the radiation detection sensitivity of this EPD appeared to be $3.8\;cps/Gy{\cdot}h^{-1}$. The linearity of radiation response was kept within 8% of the dose equivalent ranges of $10{\mu}Sv{\sim}4Sv$ and the angular dependence was under less than 4% in angles of ${\pm}60^{\circ}$. It was confirmed that the energy response range was in $60{\sim}1,250keV$ given in the ISO standard. This EPD satisfied the international criteria for the EPD in the mechanical and the environmental performance test for 9 test categories according to IEC 61526.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.87-95
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• 2003

The fabrication process and the structure of PIN semiconductor detectors have been designed optimally by simulation for doping concentration and width of p+ layer, impurities re-contribution due to annealing and the current distribution due to guard ring at the sliced edges. The characteristics to radiation response has been also simulated in terms of Monte Carlo Method. The device has been fabricated on n type, $400\;{\Omega}cm$, orientation <100>, Floating-Zone silicon wafer using the simulation results. The leakage current density of $0.7nA/cm^2/100{\mu}m$ is achieved by this process. The good linearity of radiation response to Cs-137 was kept within the exposure ranges between 5 mR/h and 25 R/h. This proposed process could be applied for fabricating a PIN semiconductor detector for measuring individual dose.

• Progress in Medical Physics
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• v.22 no.3
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• pp.124-130
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• 2011

In this study the dosimetric evaluation for a biological sample irradiated by gamma rays from Cs-137 irradiator (Gamma Irradiator, Chiyoda Technol Co., Japan) was performed for radiobiological experiment. A spherical water with a diameter of 3 cm was assumed as a biological sample. The absorbed dose were determined by the air kerma based dosimetric calculation system. The theoretical and Monte Carlo calculations (MCNPX) were performed and compared to evaluate measured air kerma and determined absorbed dose respectively. As a result of comparison with theoretical calculation, the measured air kerma was in good agreement within 3.1% at the distance of 100 and 200 cm from the source. In comparison with Monte Carlo results the determined absorbed dose along the central axis was in good agreement within 1.9% and 3.7% at 100 cm and 200 cm respectively. Although the preliminary results were obtained in this study these results were used as a basis of dosimetric evaluation for radiobiological experiment. Extended study will be performed to evaluate the dose in various conditions of biological samples.

• Journal of Radiation Protection and Research
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• v.24 no.1
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• pp.39-43
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• 1999

Thermoluminescent (TL) response characteristics of a thin LiF:Mg,Cu,Na,Si Teflon detectors have been studied for use in beta radiation detection. The detectors were fabricated from a mixture of LiF:Mg,Cu,Na,Si phosphor and Teflon powder which was molded into a thin disk form of $50mg/cm^2$ thickness. These detectors were irradiated to beta fields of $^{147}Pm,\;^{204}Tl\;and\;^{90}Sr/^{90}Y$ sources with a covering of Kapton foil ($2mg/cm^2$) and photon irradiation was carried out with a $^{137}Cs$ source at the Korea Atomic Energy Research Institute (KAERI). Batch uniformity was estimated to be 4.7% and the beta dose response presented linear relationship from 0.1 mGy to 100 Gy. The beta energy responses of thin detectors normalized to $^{137}Cs$ were presented as 0.46, 1.09 and 1.06 for $^{147}Pm,\;^{204}Tl\;and\;^{90}Sr/^{90}Y$ beta rays, respectively. The evaluated values for angular responses were $0.93{\pm}0.03\;(^{147}Pm),\;0.94{\pm}0.04\;(^{204}Tl),\;and\;0.92{\pm}0.05\;(^{90}Sr/^{90}Y)$. The results satisfied well a proposed ISO Standard for beta ray dosimeters.

• Analytical Science and Technology
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• v.5 no.1
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• pp.57-61
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• 1992

For the neutron spectrum measurement, $^6Li$ neutron spectrometer system is installed. The characteristic of the $^6Li$ detector are investigated using a $^{137}Cs$ and $^{207}Bi$ point source, and the neutron capture peaks and the pulse height spectrum using an $^{214}Am-Be$ neutron source are measured. Furthermore, the pulse height spectrum for the irradiation time variation from the (214)^Am-Be neutron source, and for the distance variation between detector and source, and the threshold variation of discriminator are measured.

• Journal of Sensor Science and Technology
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• v.6 no.4
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• pp.290-297
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• 1997

In this study, the radiation monitoring system using CsI(TI) scintillation counter is developed for the measurement of radiation distribution in the field of high dose level. When the inner diameter of collimator is 8 mm, we have realized the optimum detecting efficiency and spatial resolution. At that time, the position resolution was 10 cm at 1 m from the system. And experimental results indicated that the energy resolution of the system were 10 % for 662 keV of Cs-137, 7.6 % for 1.17 MeV of Co-60, and 5.8 % for 1.33 MeV of Co-60. Also, we have shown that the real radiation distribution images may be obtained by our measurement system.