• Journal of Radiation Protection and Research
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• 제39권3호
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• pp.134-141
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• 2014

방사선요법은 항암 치료에서 널리 이용되는 요법으로, 항암치료에 저선량 방사선을 이용하는 것에 대한 관심이 증가되고 있고, 저선량 방사선의 다양한 생물학적 효과가 있음이 보고되고 있다. 그러므로 본 연구에서는 마우스 모델에서 저선량 방사선이 면역반응에 어떠한 영향을 미치는지, 또한 이를 감지할 수 있는지를 조사하였다. C57BL/6 마우스에 $^{137}Cs$ 선원을 이용하여 연속 3일간 총 90 mGy의 저선량 방사선을 전신 조사한 후 마지막 방사선 조사 2, 14, 28일 후에 마우스를 희생시켜 말초 혈액 세포수, 비장 세포수, 비장 내 면역세포의 비율과 활성화 정도를 분석하였다. 말초 혈액 검사를 통해, 저선량 방사선 조사군에서 적혈구와 혈소판 수의 유의적 변화는 관찰할 수 없었으며, 백혈구 수는 마지막 방사선 조사 후 2일째에 선량-의존적인 감소를 보였으나, 점차 회복되는 경향을 나타냈다. 비장세포 수도 2일째 감소를 보였지만 서서히 그 수가 증가됨을 확인하였다. 2일과 14일째에 비장세포의 Foxp3 mRNA가 감소된 반면, CD4 T 세포와 CD69 양성세포가 증가되었다. 마우스에서 분할 저선량 방사선을 전신조사한 결과, 방사선조사군에서 특이적인 임상 증상이나 유의적인 체중감소를 보이지 않았다. 본 연구에서는 마우스를 대상으로 저선량을 분할 조사하였을 경우에도 면역학적 변화를 확인할 수 있으며 이를 통해 향후 저선량 방사선의 생물학적 효과를 뒷받침하는 자료로 활용할 수 있으리라 기대한다.

• Journal of Radiation Protection and Research
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• 제37권4호
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• pp.231-236
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• 2012

This study derived measures to reduce exposure doses by identifying factors which affect the external radiation dose rate of patients treated with radiopharmaceuticals for PET-CT tests. The external radiation dose rates were measured on three parts of head, thorax and abdomen at a distance of 50cm from the surface of 60 PET-CT patients. It showed there are changes in factors affecting the external radiation dose rate over time after the administration of F-18 FDG. The external radiation dose rate was lower in the patients with more water intake than those with less water intake before the injection of radiopharmaceuticals at all three points: right after the injection of radiopharmaceuticals (average 4.17 mins), after the pre-PEET-CT urination step (average 77.47 mins), and right after the PET-CT test (average 114.15 mins). The study also found there is a need to increase the amount of water intake before the injection of radiopharmaceuticals in order to maintain a low external radiation dose rate in patients. This strategy is only possible under the assumption that the quality of the video has not changed after conducting this study on the relations between the image and quality. This study also found a need to use radiopharmaceuticals with the minimum amount needed for each patient because F-FDG doses affects the external radiation dose rate at the point right after the injection of radiopharmaceuticals. Urination frequency was the most significant factor to affect the external radiation dose rates at the point right after the PET-CT test and the point after the pre-PET-CT urination step. There is a need to realize the strategy to increase the urination frequency of patients to maintain the external radiation dose rate low (average 77.47 mins) before and after the injection of radiopharmaceuticals. In addition, at this point, there is a need to take advantage of personal strategies because the external radiation dose rate is lower if the fasting time is shorter, the contrast medium is used, and the amount of water intake is increased after the administration of radiopharmaceuticals. Finally this study found the need to be able to generalize these findings through an in-depth research on the factors affecting the external radiation dose rate, which includes radiopharmaceutical dose, urination frequency, the amount of water intake, fasting time and the use of contrast medium.

• 한국의학물리학회지:의학물리
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• 제27권3호
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• pp.146-155
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• 2016

As the probability of exposure to radiation increases due to an increase in the use of radioisotopes and radiation generators, the importance of a radiation safety management field is being highlighted. We intend to help radiation workers with exposure management by identifying the degree of radiation exposure and contamination to determine an efficient method of radiation safety management. The personal exposure doses of the radiation workers at the Korea Institute of Radiological & Medical Sciences measured every quarter during a five-year period from Jan. 1, 2011 till Dec. 31, 2015 were analyzed using a TLD (thermoluminescence dosimeter). The spatial dose rates of radiation-controlled areas were measured using a portable radioscope, and the level of surface contamination was measured at weekly intervals using a piece of smear paper and a low background alpha/beta counter. Though the averages of the depth doses and the surface doses in 2012 increased from those in 2011 by about 14%, the averages were shown to have decreased every year after that. The exposure dose of 27 mSv in 2012 increased from that in 2011 in radiopharmaceutical laboratories and, in the case of the spatial dose rate, the rate of decrease in 2012 was shown to be similar to the annual trend of the whole institute. In the case of the surface contamination level, as the remaining radiation-controlled area with the exception of the I-131 treatment ward showed a low value less than $1.0kBq/m^2$, the annual trend of the I-131 treatment ward was shown to be similar to that of the entire institute. In conclusion, continuous attention should be paid to dose monitoring of the radiation-controlled areas where unsealed sources are handled and the workers therein.

• 전기전자학회논문지
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• 제19권2호
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• pp.193-200
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• 2015

본 논문에서는 CMOS 이미지 센서를 사용한 방사선 측정 알고리즘 및 장치의 구성을 제안한다. CMOS 이미지 센서를 사용한 방사선 측정 알고리즘은 CMOS 이미지 센서에 입사된 방사선 입자 판별 알고리즘과 CMOS 이미지 센서로 매초 수 십장의 이미지에 입사된 방사선 입자에 대한 픽셀 수의 누적 및 평균을 기준으로 하는 방사선 수치 측정 알고리즘을 사용한다. CMOS 이미지 센서에 입사된 방사선 입자 판별 알고리즘은 입사된 방사선 입자의 이미지를 R, G, B로 분할하고 각각의 이미지에 대해 명암 및 백그라운드와 입자를 구별할 수 있는 임계값 설정 조정을 통하여 측정한다. 방사선 수치 측정 알고리즘은 설정된 주기에 따른 CMOS 이미지 센서로 매초 수 십장의 이미지에 입사된 방사선 입자수를 누적 저장, 평균을 통하여 방사선 수치를 측정한다. 제안된 알고리즘의 검증을 위한 하드웨어 장치는 CMOS 이미지 센서 및 이미지 시그널 프로세서부, 제어부, 전원회로부, 디스플레이부 등으로 구성된다. 제안된 CMOS 이미지 센서를 사용한 방사선 측정에 관하여 실험한 결과는 다음과 같다. 첫 번째로 저가의 CMOS 이미지 센서를 사용하여 방사선 입자 판별 측정 실험을 통해 고가의 GM Tube의 측정 구간별 특성과 대체로 유사한 특성을 나타낼 수 있음을 확인할 수 있었다. 두 번째로 저가의 CMOS 이미지 센서로 방사선 수치 측정 실험을 통해 고가의 GM Tube가 나타내는 선형 특성과 대체로 유사한 특성을 나타냄을 확인할 수 있었다.

• Safety and Health at Work
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• 제12권4호
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• pp.445-451
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• 2021

Background: This study aimed to evaluate the reliability and validity of the self-administered questionnaire for Korean radiation workers. Methods: From May 24, 2016, to June 30, 2017, 20,608 participants completed the questionnaire, providing information on sociodemographics, lifestyle, work history and practices, medical radiation exposure, and medical history, which was linked to the National Dose Registry and the National Cancer Registry. The validity of the questionnaire was evaluated using the responses of 20,608 workers, and reliability was evaluated using the responses of 3043 workers who responded to the survey twice. Results: Responses concerning demographic characteristics and lifestyle showed reliability with a moderate-to-high agreement (kappa: 0.43-0.99), whereas responses concerning occupation and medical radiation exposure had a wide range of agreement (kappa: 0.05-0.95), possibly owing to temporal variability during employment. Regarding validity, responses to the question about the first year of employment had an excellent agreement with the national registry (intraclass correlation coefficient = 0.9); however, responses on cancer history had a wide range of agreement (kappa: 0.22-0.85). Conclusion: Although the reliability and validity of the questionnaire were not distinguished by demographic characteristics, they tended to be low among participants whose occupational radiation exposure was minimal. Overall, the information collected can be reliable for epidemiological studies; however, caution must be exercised when using information such as medical exposure and work practices, which are prone to temporal variability.

• 전기전자학회논문지
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• 제15권2호
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• pp.143-148
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• 2011

MOS (Metal-Oxide Semconductor) devices among the most sensistive of all semiconductors to radiation, in particular ionizing radiation, showing much change even after a relatively low dose. The necessity of a radiation dosimeter robust enough for the working environment has increased in the fields of aerospace, radio-therapy, atomic power plant facilities, and other places where radiation exists. The power MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) has been tested for use as a gamma radiation dosimeter by measuring the variation of threshold voltage based on the quantity of dose, and a maximum total dose of 30 krad exposed to a $^{60}Co$ ${\gamma}$-radiation source, which is sensitive to environment parameters such as temperature. The gate oxide structures give the main influence on the changes in the electrical characteristics affected by irradiation. The variation of threshold voltage on the operating temperature has caused errors, and needs calibration. These effects can be overcome by adjusting gate oxide thickness and implanting impurity at the surface of well region in MOSFET.

• 한국음향학회지
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• 제14권5호
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• pp.58-62
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• 1995

무한배플에 고정된 사각형 진동체에 대한 자기방사 임피던스를 극좌표를 이용한 적분식으로 표시하고 이를 방사저항과 방사 리액턴스로 분리하여 수치해석 하였다. 해석의 결과를 접근방법이 다른 이론식의 결과와 비교하였다. 수치해석의 결과 다른 방법들은 저주파 영역에서 근사식을 사용하여 보정을 해준 반면 본 논문에서 사용된 적분식은 전 주파수 영역에서 제한조건 없이 잘 맞음을 보였다.

• The Journal of the Acoustical Society of Korea
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• 제28권2E호
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• pp.51-59
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• 2009

Mutual radiation impedance becomes more important in the design and analysis of acoustic transducers for higher power, better beam pattern, and wider bandwidth at low frequency sonar systems. This review paper focused on literature survey about the researches of mutual radiation impedance in the acoustic transducer arrays over 60 years. The papers of mutual radiation impedance were summarized in terms of transducer array structures on various baffle geometries such as planar, cylindrical, spherical, conformal, spheroidal, and elliptic cylindrical arrays. Then the computation schemes of solving conventional quadruple integral in the definition of mutual radiation impedance were surveyed including spatial convolution method, which reduces the quadruple integral to a double integral for efficient computation.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.5589-5594
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• 2015

Cystitis and proctitis are defined as inflammation of bladder and rectum respectively. Haemorrhagic cystitis is the most severe clinical manifestation of radiation and chemical cystitis. Radiation proctitis and cystitis are major complications following radiotherapy. Prevention of radiation-induced haemorrhagic cystitis has been investigated using various oral agents with minimal benefit. Bladder irrigation remains the most frequently adopted modality followed by intra-vesical instillation of alum or formalin. In intractable cases, surgical intervention is required in the form of diversion ureterostomy or cystectomy. Proctitis is more common in even low dose ranges but is self-limiting and improves on treatment interruption. However, treatment of radiation proctitis is broadly non-invasive or invasive. Non-invasive treatment consists of non-steroid anti-inflammatory drugs (NSAIDs), anti-oxidants, sucralfate, short chain fatty acids and hyperbaric oxygen. Invasive treatment consists of ablative procedures like formalin application, endoscopic YAG laser coagulation or argon plasma coagulation and surgery as a last resort.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.285-294
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• 2023

Autonomous radiation source detection has long been studied for radiation emergencies. Compared to conventional data-driven or path planning methods, deep reinforcement learning shows a strong capacity in source detection while still lacking the generalized ability to the geometry in unknown environments. In this work, the detection task is decomposed into two subtasks: exploration and localization. A hierarchical control policy (HC) is proposed to perform the subtasks at different stages. The low-level controller learns how to execute the individual subtasks by deep reinforcement learning, and the high-level controller determines which subtasks should be executed at the current stage. In experimental tests under different geometrical conditions, HC achieves the best performance among the autonomous decision policies. The robustness and generalized ability of the hierarchy have been demonstrated.