• Journal of Radiation Protection and Research
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• v.47 no.3
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• pp.158-166
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• 2022

Background: The effects of radiation on the health of radiation workers who are constantly susceptible to occupational exposure must be assessed based on an accurate and reliable reconstruction of organ-absorbed doses that can be calculated using personal dosimeter readings measured as H_p(10) and dose conversion coefficients. However, the data used in the dose reconstruction contain significant biases arising from the lack of reality and could result in an inaccurate measure of organ-absorbed doses. Therefore, this study quantified the biases involved in organ dose reconstruction and calculated the bias-corrected H_p(10)-to-organ-absorbed dose coefficients for the use in epidemiological studies of Korean radiation workers. Materials and Methods: Two major biases were considered: (a) the bias in H_p(10) arising from the difference between the dosimeter calibration geometry and the actual exposure geometry, and (b) the bias in air kerma-to-H_p(10) conversion coefficients resulting from geometric differences between the human body and slab phantom. The biases were quantified by implementing personal dosimeters on the slab and human phantoms coupled with a Monte Carlo method and considered to calculate the bias-corrected H_p(10)-to-organ-absorbed dose conversion coefficients. Results and Discussion: The bias in H_p(10) was significant for large incident angles and low energies (e.g., 0.32 for right lateral at 218 keV), whereas the bias in dose coefficients was significant for the posteroanterior (PA) geometry only (e.g., 0.79 at 218 keV). The bias-corrected H_p(10)-to-organ-absorbed dose conversion coefficients derived in this study were up to 3.09- fold greater than those from the International Commission on Radiological Protection publications without considering the biases. Conclusion: The obtained results will aid future studies in assessing the health effects of occupational exposure of Korean radiation workers. The bias-corrected dose coefficients of this study can be used to calculate organ doses for Korean radiation workers based on personal dose records.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.754-756
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• 1999

In this paper, we have developed a high-sensitivity SNRD(Semiconductor Nuclear Radiation Detector) using silicon PIN photodiode. The SNRD is constructed with silicon PIN photodiode(S3590-05), preamplifier and shaping amplifier. To show the effectiveness of SNRD, nuclear radiation experiments are conducted with $\gamma$-ray Ba-133, Cs-137 and Co-60. The SNRD is different in characteristics of the energy spectrum to scintillation detectors. However, the SNRD have a good linearity on $\gamma$-ray energy and activity. The results of this paper can be applied to electronic personal dosimeter.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.724-726
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• 2000

일반적으로 개인방사선감시에 열형광선량계와 필름배지가 공식 개인선량계로 이용되어 왔고 현재까지도 가장 보편적으로 사용되고 있다. 하지만 최근에는 Si 다이오드와 G-M관을 이용한 능동형 개인피폭선량계가 개발 보급되고 있다. 개인피폭선량계는 누적선량을 실시간으로 알 수 있다는 장점을 가지고 있을 뿐만 아니라 선량률에 관한 정보도 제공하므로 높은 비용부담에도 불구하고 피폭관리의 용이함으로 인해 주목을 받고 있다. 따라서 본 연구는 수입에 의존해 온 개인피폭선량계를 대체하기 위해 반도체형 방사선 검출기를 설계하여 다양한 서비스를 부가할 수 있는 개인피폭선량계를 자체개발고, 선량계의 운영 및 판독을 위한 장치를 개발하였다.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.179-183
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• 2016

Background: As an important detecting device, TLD is a widely used in the radiation monitoring. It is essential for us to study the property of detecting element. The aim of this study is to calculate the thermo-luminescence efficiency of TL elements. Materials and Methods: A batch of thermo-luminescence elements were irradiated by the filtered X-ray beams of average energies in the range 40-200 kVp, 662 keV $^{137}Cs$ gamma rays and then the amounts of lights were measured by the TL reader. The deposition energies in elements were calculated by theory formula and Monte Carlo simulation. The unit absorbed dose in elements by photons with different energies corresponding to the amounts of lights was calculated, which is called the thermo luminescent efficiency (${\eta}^{(E)}$). Because of the amounts of lights can be calculated by the absorbed dose in elements multiply ${\eta}^{(E)}$, the ${\eta}^{(E)}$ can be calculated by the experimental data (the amounts of lights) divided by absorbed dose. Results and Discussion: The deviation of simulation results compared with theoretical calculation results were less than 5%, so the absorbed dose in elements was calculated by simulation results in here. The change range of ${\eta}^{(E)}$ value, relative to 662 keV $^{137}Cs$ gamma rays, is about 30% in the energy range of 33 keV to 662 keV, is in accordance by the comparison with relevant foreign literatures. Conclusion: The ${\eta}^{(E)}$ values can be used for updating the amounts of lights that are got by the direct ratio assumed relations with deposition energy in TL elements, which can largely reduce the error of calculation results of the amounts of lights. These data can be used for the design of individual dosimeter which used TLD-2000 thermo-luminescence elements, also have a certain reference value for manufacturer to improve the energy-response performance of TL elements by formulation adjustment.

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.473-476
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• 2012

The PET-MRI which has been installed and being managed recently uses both magnetic field and radiation. Most radiation workers wear a thermoluminescenct dosimeter (TLD) as a personal radiation dosimeter, and the TLD is affected both by a magnetic field and radiation. In this research, the same amount of X-ray was applied to 36 TLDs, and the changes in the dose of the 32 TLDs exposed to magnetic field at the location where its intensity of the magnetic resonance imaging (MRI) was about 5000 Gauss for eight hours with one-hour unit and that of the four TLDs not exposed to magnetic field were compared and checked. The measurement result showed that exposure dose of the TLD attached to the MRI changed irregularly depending on the amount of exposure time. Therefore, the TLD whose amount of changes little in the environment of a MRI is demanded to be developed.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.841-847
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• 2021

Related institutions that use radiation are diverse in Korea, such as research, medical care, and education. Recently, the number of examinations and visits to medical institutions is increasing. As a result, the number of radiological examinations in medical institutions is increasing. Radiation safety management is necessary as well as exposure of radiation workers. For safety management, first of all, it is necessary to wear the personal exposure dosimeter correctly and measure it accurately after wearing it. This study tries to evaluate and verify the measurement straightness of PLD devices by radiation of a diagnostic generator. Radiation division irradiation time interval was measured after irradiating 10 times at 10, 30, and 60 sec and irradiating the irradiation distance from 30 to 100 cm at 10 cm intervals to measure the change in absorbed dose depending on the distance. As a result, there was no difference in absorbed dose by time interval. This is considered to be helpful in various studies by using a diagnostic generator for the study of high absorbed dose.

• Journal of Radiation Protection and Research
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• v.39 no.4
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• pp.213-217
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• 2014

Medical operations and diagnosis using interventional radiology techniques have been increased. The management and monitoring of occupational radiation exposure to the staff of interventional radiology become important, specially because they stand in close proximity to the patient. The operational radiation protection quantity, Hp(10) which can be obtained from personal dosimeter do not always represent the effective dose to the staff. So, in this study, to estimate the critical organ doses to the staff of interventional radiology, Monte Carlo calculations with mathematical human phantom and dose measurements with personal dosimeters were carried out for the major interventional radiology procedures using C-arm. Results showed that the values of Hp(10) measured by personal dosimeters were higher than critical organ doses which were calculated. And the calculated dose to thyroids was much higher than those of other critical organ doses. For the proper radiation protection of the medical staff of interventional radiology, additional radiation protection for thyroids as well as for whole body shielding like wearing a lead apron should be considered.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.854-860
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• 2014

Workers engaged in car inspection works have been exposed to many occupational hazards including noise, particulate matter, and volatile organic substances. Noise-induced hearing loss(NIHL) is one of the leading health hazards among Korean workers. The aim of this study is to evaluate the noise levels in several car inspection shops by introducing the evaluation methods of KMOEL/OSHA and ACGIH. Six sites in central area of Korea were selected to monitor the noise levels of workers by personal and area sampling methods for two consecutive days in spring, summer, fall and winter seasons. Dosimeters have been used for this noise monitoring program. Obtained noise levels by the evaluation method according to KMOEL/OSHA are the range of 50.2~88.2 dB(A), these are lower than KOEL/OSHA standards level of 90 dB(A). But highest noise by ACGIH's evaluation methodology is recorded 92.3 dB(A) and is greater than NIHL standard level of 85 dB(A). So that many workers may be exposed to the dangerous noise environment. The higher the car inspection loads daily, the higher the noise levels in the sites. Seasonal fluctuation of noise levels at the process might give monitoring results with high variations. Area noise levels showed higher than those of personal sampling, which illustrate some high noise spots in the car inspection areas.

• The Journal of the Korea Contents Association
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• v.12 no.3
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• pp.244-250
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• 2012

The results of analyzing the difference between performances of individual dosimeters on this research subjecting the PLD and TLD, which are the official personal dosimeters, through dosimetry are as follows. After scanning the integral dose using an automatic scanner, the values of two devices that went through dose adjustment process had a statistical difference in TLD and PLD measurements under each filming conditions which were 70kVp, 200mA, 0.012sec and 42kVp, 100mA, and 0.012sec (p<0.001 and p<0.001 respectively). As for the difference of measurement value between DAP and the two particles under 70kVp, 200mA, 0.012sec filming condition, TLD had a value lower than DAP average value by $44.2mGy{\cdot}cm^2$ and PLD had a value of $246.8mGy{\cdot}cm^2$ which was lower than DAP average value by $15.5mGy{\cdot}cm^2$, while under 42kVp, 100mA, 0.012sec filming condition, TLD had a value lower than DAP average value by $17.9mGy{\cdot}cm^2$ and PLD had a value of $82.6mGy{\cdot}cm^2$ which was lower than DAP average value by 7.6$mGy{\cdot}cm^2$. Also, compared to PLD, each of 10 devices measured dose value in TLD had a larger deviation between the particles, and for a reproducibility test which repeatedly measured one particle, PLD had ${\pm}1%$ which was lower than TLD's ${\pm}2%$. As such, PLD had a superior performance result in dose measurement capacities aspect compared to TLD, and therefore we could verify that PLD is more appropriate and advantageous in managing radiation-related task performing worker's personal radiation exposure management in the diagnostic radiation field.

• The Journal of the Korea Contents Association
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• v.16 no.8
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• pp.419-426
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• 2016

The research is done to analyze the change of personal dosimeter according to the elapsed times(24 hours, 1 week, 2 weeks, 3 weeks, 4 weeks) and magnetic field and find out the effective exposure treatment for radiation workers. At first, research the heat treatment and radiation of grouped TLD and keep them in different environments-exposed separately to observe the consequences of glow curve and the level of radiation exposure. As a result, we could find that 24 hours passing TLD group showed the difference in glow curve and the level of radiation. This can be considered as the change caused by magnetic exposure. Also the average radiation exposure level of TLD group, unexposed to the magnetic field, was 15.41 mSv. And the average radiation exposure level of TLD group, exposed to the magnetic field, was 14.83 mSv which decreased the biggest amount(3.80%) among the other groups. If a radiation worker, who works in PET-MRI room, uses TLD as a personal dosimeter, the level of real radiation exposure caused by exposure to the magnetic field won't change significantly as recorded at a regular record cycle but with not regular record but interim record, the lower exposure dose will be appeared than the real level of radiation.