• Journal of Radiation Protection and Research
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• 제47권4호
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• pp.204-213
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• 2022

Background: The accident at the Fukushima Daiichi nuclear power plant increased the level of anxiety related to the radioactive contamination of various foods sourced in Japan. Particularly, after the accident, the detection of artificial radionuclides in locally produced foods raised food safety concerns. In this study, the radioactivity concentrations and annual ingestions of ⁴⁰K and ¹³⁷Cs in food products commonly and frequently consumed by the general public were investigated, and the annual effective dose of each was evaluated. Materials and Methods: The 2016-2018 data from the Radiation Safety Management Report released by the Korea Nuclear Safety Technology Center was referenced for the evaluation of the amounts of ⁴⁰K and ¹³⁷Cs contained in food. Using the food-ingestion survey mentioned above as a reference, we selected 62 foods to include in our radioactivity concentration and dose assessment. We also developed a questionnaire and evaluated the responses from the subjects who answered the questionnaire. Results and Discussion: The radioactivity concentration of ¹³⁷Cs was found to be close to or below the level of minimum detectable activity. Additionally, the annual ingestion of 62 foods was 294.77 kg/yr, the effective doses from ⁴⁰K and ¹³⁷Cs were 136.4 and 0.163 μSv/yr, respectively. Conclusion: Thus, the findings confirmed that the effective dose from ⁴⁰K and ¹³⁷Cs in food tends to be lower than the effective dose limit of 1 mSv/yr suggested by the International Commission on Radiological Protection (ICRP) Publication 60. The questionnaire developed in this study is expected to be useful for estimating the annual effective dose status of Korean adults who consume foods containing ⁴⁰K and ¹³⁷Cs.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2002년도 춘계학술대회 논문집
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• pp.117-118
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• 2002

본 연구에서는 지하수로부터 방출된 실내라돈오염을 해석하기 위한 수학적 모델에서 모델인자들의 불확실성을 고려하고 인체축적량을 정량적으로 해석하는 PBPK모델을 사용하여 호흡을 통한 라돈의 인체축적량을 보다 현실적으로 평가하려고 한다. 우선, 전에 사용한 3 구역모델을 샤워실과 화장실을 구분하는 경계가 없다는 국내실정을 감안하여 보다 현실적으로 개량한 2-구역 모델을 개발하였다. (중략)

• Tuberculosis and Respiratory Diseases
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• 제84권2호
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• pp.96-104
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• 2021

Background: Many chronic obstructive pulmonary disease (COPD) patients receiving monotherapy continue to experience symptoms, exacerbations and poor quality of life. This study aimed to assess the efficacy and safety of direct switch from once-daily tiotropium (TIO) 18 ㎍ to indacaterol/glycopyrronium (IND/GLY) 110/50 ㎍ once daily in COPD patients in Korea. Methods: This was a randomized, open-label, parallel group, 12-week trial in mild-to-moderate COPD patients who received TIO 18 ㎍ once daily for ≥12 weeks prior to study initiation. Patients aged ≥40 years, with predicted post-bronchodilator forced expiratory volume in 1 second (FEV₁) ≥50%, post-bronchodilator FEV₁/forced vital capacity <0.7 and smoking history of ≥10 pack-years were included. Eligible patients were randomized in a 1:1 ratio to either IND/GLY or TIO. The primary objective was to demonstrate superiority of IND/GLY over TIO in pre-dose trough FEV₁ at week 12. Secondary endpoints included transition dyspnea index (TDI) focal score, COPD assessment test (CAT) total score, and rescue medication use following the 12-week treatment, and safety assessment. Results: Of the 442 patients screened, 379 were randomized and 347 completed the study. IND/GLY demonstrated superiority in pre-dose trough FEV₁ versus TIO at week 12 (least squares mean treatment difference [Δ], 50 mL; p=0.013). Also, numerical improvements were observed with IND/GLY in the TDI focal score (Δ, 0.31), CAT total score (Δ, -0.81), and rescue medication use (Δ, -0.09 puffs/day). Both treatments were well tolerated by patients. Conclusion: A direct switch from TIO to IND/GLY provided improvements in lung function and other patient-reported outcomes with an acceptable safety profile in patients with mild-to-moderate airflow limitation.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1830-1837
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• 2023

The thermal cutting of contaminated or activated metals during decommissioning nuclear power plants inevitably results in the release of radioactive aerosol. Since radioactive aerosols are pernicious particles that contribute to the internal dose of workers, air conditioning units with a HEPA filter are used to remove radioactive aerosols. However, a HEPA filter cannot be used permanently. This study evaluates the efficiency and lifetime of filters in actual metal cutting condition using a plasma arc cutter and a high-resolution aerosol detector. The number concentration and size distribution of aerosols from 6 nm to 10 ㎛ were measured on both the upstream and downstream sides of the filter. The total aerosol removal efficiency of HEPA filter satisfies the standard of removing at least 99.97% of 0.3 ㎛ airborne particles, even if the pressure drop increases due to dust feeding load. The pressure drop and particle size removal efficiency at 0.3 ㎛ of the HEPA filter were found to increase with repeated cutting experiments. By contrast, the efficiency of used HEPA filter reduced in removing nano-sized aerosols by up to 79.26%. Altogether, these results can be used to determine the performance guidance and replacement frequency of HEPA filters used in nuclear power plants.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1752-1757
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• 2017

The aim of this study is to evaluate the radioactivity levels and radiological impacts of representative black sand samples collected from different locations in the Rashid area, Egypt. These samples were prepared and then analyzed using the high-resolution gamma ray spectroscopy technique with a high-purity germanium detector. The activity concentration ($A_c$), minimum detectable activity, absorbed gamma dose rate, external hazard index ($H_{ex}$), annual effective dose rate equivalent, radium equivalent, as well as external and internal hazard index ($H_{ex}$ and $H_{in}$, respectively) were estimated based on the measured radionuclide concentration of the $^{238}U$($^{226}Ra$) and $^{232}Th$ decay chains and $^{40}K$. The activity concentrations of the $^{238}U$, $^{232}Th$ decay series and $^{40}K$ of these samples varied from $45.11{\pm}3.1Bq/kg$ to $252.38{\pm}34.3Bq/kg$, from $64.65{\pm}6.1Bq/kg$ to $579.84{\pm}53.1Bq/kg$, and from $403.36{\pm}20.8Bq/kg$ to $527.47{\pm}23.1Bq/kg$, respectively. The activity concentration of $^{232}Th$ in Sample 1 has the highest value compared to the other samples; this value is also higher than the worldwide mean range as reported by UNSCEAR 2000. The total absorbed gamma dose rate and the annual effective dose for these samples were found to vary from 81.19 nGy/h to 497.81 nGy/h and from $99.86{\mu}Sv/y$ to $612.31{\mu}Sv/y$, which are higher than the world average values of 59 nGy/h and $70{\mu}Sv/y$, respectively. The $H_{ex}$ values were also calculated to be 3.02, 0.47, 0.63, 0.87, 0.87, 0.51 and 0.91. It was found that the calculated value of $H_{ex}$ for Sample 1 is significantly higher than the international acceptable limit of <1. The results are tabulated, depicted, and discussed within national and international frameworks, levels, and approaches.

• The Korean journal of internal medicine
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• 제39권2호
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• pp.338-346
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• 2024

Background/Aims: Systemic lupus erythematosus (SLE) responder index (SRI)-4 response has been achieved with belimumab treatment in patients with moderate disease activity in cornerstone clinical trials and following studies. However, most studies involved patients treated with a mean prednisolone-equivalent dose of approximately 10 mg/d and focused on the steroid-sparing effect of belimumab. We aimed to identify the effect of belimumab in patients with mild-to-moderate SLE who were treated with low-dose or no corticosteroids. Methods: We retrospectively reviewed the electronic medical records of patients treated with belimumab for at least 6 months between May 2021 and June 2022. The primary endpoint was SRI-4 response at 6 months. Results: Thirty-one patients were included (13 low dose- and 18 steroid non-users). The mean age was 39.2 ± 11.4 years, and 90.3% of patients were female. The baseline Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) score was 6.0 (4.0-9.0). The primary endpoint was achieved in 32.3% (10/31) of patients. Significant improvements in anemia, C4 levels, and SELENA-SLEDAI score were observed during treatment. Univariate analysis showed that the baseline SELENA-SLEDAI and arthritis were significantly associated with SRI-4 response at 6 months, and only the SELENA-SLEDAI remained significant (p = 0.014) in multivariate analysis. Conclusions: This cohort study is the first to report the efficacy of belimumab after minimizing the effect of corticosteroids. Belimumab showed efficacy in improving the SELENA-SLEDAI score, anemia, and low C4 in patients who did not receive corticosteroids or received only low doses.

• Journal of Radiation Protection and Research
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• 제33권4호
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• pp.183-196
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• 2008

원전주변의 주민에 대한방사선량의 대부분을 음식물 섭취에 의한 내부피폭이 차지하고 있다. 그러나 우리나라 원전에 적용하고 있는 음식물 섭취 관련 인자는 1989년 한국원자력연구소가 고리원전 주변지역을 대상으로 수행한 현장조사 결과를 계속 적용하고 있어 최근의 식습관 변화를 적절히 반영하지 못하고 있다. 또한 우리나라는 미국 NRC (Nuclear Regulatory Commission) 에서 적용하고 있는 최대개인에 근거하여 음식물 섭취율을 결정하고 있다. 그러나 최근의 ICRP (International Commission on Radiological Protection) 의 권고 및 유럽의 관련 지침에서는 결정집단 또는 결정집단을 대표하는 개인에 대해 선량을 평가토록 권고하고 있다. 따라서 이러한 식습관의 변화추이나 피폭평가대상에 대한 국제적인 권고기준에 준하는 음식물 섭취율 설정방법에 대한연구가 필요하다. 보건복지가족부에서는 국민건강증진법에 의거 매 3년마다 전국 규모의 국민의 식품 및 영양섭취실태 조사를 실시하고 있다. 따라서 본 연구에서는 이러한 정부조사자료를 활용하여 주기적으로 음식물 섭취량 자료를 갱신할 수 있는 방안을 연구하였다. 보건복지가족부에서 $2001{\sim}2002$년에 수행한 국민영양조사원자료(raw data)를 분석하여 결정집단을 대표하는 개인의 음식물 섭취율을 결정하는데 이용할 수 있는 기초통계량을 제시하고, 또한 현재 국내 원전에서 적용하고 있는 최대개인의 음식물 섭취율을 재설정하였다.

• Tuberculosis and Respiratory Diseases
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• 제85권1호
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• pp.80-88
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• 2022

Background: Although it is known that inhaled corticosteroid (ICS) use may increase the risk of respiratory infection, its influence on the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains unknown. Thus, the aim of this study was to investigate the association between ICS use and the positivity of SARS-CoV-2 infection among patients with chronic respiratory diseases. Methods: Nationwide data of 44,968 individuals with chronic respiratory diseases tested for SARS-CoV-2 until May 15, 2021 were obtained from the Ministry of Health and Welfare and Health Insurance Review and Assessment Service in Korea. The positivity of SARS-CoV-2 infection was retrospectively analysed according to the prescription, type, and dose of ICS taken one year before SARS-CoV-2 test. Results: Among 44,968 individuals tested, 931 (2.1%) were positive for SARS-CoV-2. A total of 7,019 patients (15.6%) were prescribed ICS one year prior to being tested for SARS-CoV-2. Low, medium, and high doses of ICS were prescribed in 7.5%, 1.6%, and 6.5% of total cases, respectively. Among types of ICS, budesonide, fluticasone, beclomethasone, and ciclesonide were prescribed in 3.7%, 8.9%, 2.3%, and 0.6% of total cases, respectively. A multivariate analysis showed no significant increase in infection with ICS use (odds ratio, 0.84; 95% confidence interval, 0.66-1.03). Moreover, there were no associations between the positivity of infection and the dose or type of ICS prescribed. Conclusion: Prior ICS use did not increase the positivity for SARS-CoV-2 infection. Moreover, different doses or types of ICS did not affect this positivity.

• 환경생물
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• 제24권4호
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• pp.387-391
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• 2006

Manchester system 타입의 장착기중 상, 하부에 차폐체가 장착되어 있는 Henschke 장착기를 이용하여 자궁암 근접치료시 자궁 및 주변장기의 선량분포를 평가하기 위하여 치료계획수립에 사용되는 실용프로그램 결과와 몬테칼로 모의계산 결과를 비교하였다. 또한 자궁 및 주변 정상조직이 받은 선량을 계산하기 위해 ORNL(Oak Ridge National Laboratory)에서 수립한 여성의 MIRD (Medical Internal Radiation Dose)형 모의피폭체를 이용 하여 주변장기가 받는 선량을 MCNP로 계산하였다. 몬테칼로 모사에는 MCNP 4B코드를 사용하였으며, 실용계산프로그램에는 GAMMADOT를 이용하였다 MCNP계산에는 $^{192}Ir$ 선원과 장착기의 기하학적 모양을 정밀하게 모사하여 계산 오차를 줄이도록 하였으며, 치료계획용 실용계산프로그램의 계산 조건과 동일하게 치료선원의 강내 체류시간과 체류위치를 적용하여 선량을 계산하였다. 주요 선량 비교 평가점은 Manchester system에서 사용되는 4곳과 ICRU 38에서 Manchester system을 보완하기 위해 제시한 방광표면 및 직장이였다. 실용계산 결과는 MCNP모의계산의 결과와 비교했을 때 대부분 위치에서 상대오차 4% 이내의 결과를 보였고, 난형체의 차폐체 장착효과로 인한 방광과 직장에서의 선량감쇠효과는 각각 19%, 20%였다.

• Journal of Korean Society for Atmospheric Environment
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• 제17권E2호
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• pp.43-51
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• 2001

A report by the national research council in the United States suggested that many lung cancer deaths each year be associated with breathing radon in indoor air. Most of the indoor radon comes directly from soil beneath the basement of foundations. Recently, radon released from groundwater is found to contribute to the total inhalation risk from indoor air. This study presents the quantitative assessment of human exposures to radon released from the groundwater into indoor air. At first, a three-compartment model is developed to describe the transfer and distribution of radon released from groundwater in a house through showering, washing clothes, and flushing toilets. Then, to estimate a daily human exposure through inhalation of such radon for an adult. a physiologically-based pharmacokinetic(PBPK) model is developed. The use of a PBPK model for the inhaled radon could provide useful information regarding the distribution of radon among the organs of the human body. Indoor exposure patterns as input to the PBPK model are a more realistic situation associated with indoor radon pollution generated from a three-compartment model describing volatilization of radon from domestic water into household air. Combining the two models for inhaled radon in indoor air can be used to estimate a quantitative human exposure through the inhalation of indoor radon for adults based on two sets of exposure scenarios. The results obtained from the present study would help increase the quantitative understanding of risk assessment issues associated with the indoor radon released from groundwater.