Optimized inverse distance weighted interpolation algorithm for γ radiation field reconstruction

Zhang Biao,Cao Jinjia,Lin Shuang,Li Xiaomeng,Zhang Yulong,Zheng Xiaochang,Chen Wei,Song Yingming 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

The inversion of radiation field distribution is of great significance in the decommissioning sites of nuclear facilities. However, the radiation fields often contain multiple mixtures of radionuclides, making the inversion extremely difficult and posing a huge challenge. Many radiation field reconstruction methods, such as Kriging algorithm and neural network, can not solve this problem perfectly. To address this issue, this paper proposes an optimized inverse distance weighted (IDW) interpolation algorithm for reconstructing the gamma radiation field. The algorithm corrects the difference between the experimental and simulated scenarios, and the data is preprocessed with normalization to improve accuracy. The experiment involves setting up gamma radiation fields of three Co-60 radioactive sources and verifying them by using the optimized IDW algorithm. The results show that the mean absolute percentage error (MAPE) of the reconstruction result obtained by using the optimized IDW algorithm is 16.0%, which is significantly better than the results obtained by using the Kriging method. Importantly, the optimized IDW algorithm is suitable for radiation scenarios with multiple radioactive sources, providing an effective method for obtaining radiation field distribution in nuclear facility decommissioning engineering.

Intercomparison of the KAERI Reference Photon and Beta Radiation Measurements

Kim,B.H.,Kim,J.L.,Chang,S.Y.,McDonald,J.C,Murphy,M.K. 대한방사선 방어학회 1996 방사선방어학회지 Vol.21 No.4

이 논문은 최근 한국원자력연구소(KAERI)와 미국 패시픽노스웨스트 국립연구소(일명, 바텔연구소, PNNL)이 개인선량계의 성능검사를 위한 미국 ANSI N13.11 기준에 근거하여 KAERI 방사선 측정/교정실험실에서 수행한 KAERI 기준 광자 및 베타 방사선장의 국제 상호비교 측정결과를 설명하고 있다. 두 기관이 각각 자국의 일차 표준에 소급성을 갖는 방사선 검출기와 방사선 측정장치를 사용하여 자유공기중에서 광자의 조사선량(율), 공기커마(율)와 베타선의 절대흡수선량(율)을 측정한 결과, 광자선장에 대해서는 ± 2.0 %, 베타선장에 대해서는 ±1.0 %의 오차범위내에서 잘 일치하였다. 따라서 KAERI의 기준 광자 및 베타 방사선장은 국제표준에 잘 만족되고 있음이 입증되었으며 장차 방사선 도시메트리 연구개발의 국가 기술기반으로 활용될 수 있음이 확인되었다. This paper describes the results of intercomparison measurements of KAERI reference photon and beta radiation fields between the KAERI and PNNL(Pacific Northwest national Laboratory), recently performed at KAERI radiation calibration and dosimetry laboratory on the basis of the ANSI N13.11 criteria for personal dosimeter performance test. Each laboratory used her own radiation detectors or measurement devices traceable to her national primary standard in measuring the exposure rates for photon fields, the absorbed dose rates for beta radiation fields. The agreements in reference radiation measurements between two laboratories were found to be less than ±2.0 % for photon fields, ±1.0 % for beta radiation fields. Therefore, it could be concluded that KAERI reference radiation fields comply well with the international standard and thus can further serve as a national basis for the researches and developments in radiation protection dosimetry in Korea.

Feasibility of normal tissue dose reduction in radiotherapy using low strength magnetic field

Jung, Nuri Hyun,Shin, Youngseob,Jung, In-Hye,Kwak, Jungwon The Korean Society for Radiation Oncology 2015 Radiation Oncology Journal Vol.33 No.3

Purpose: Toxicity of mucosa is one of the major concerns of radiotherapy (RT), when a target tumor is located near a mucosal lined organ. Energy of photon RT is transferred primarily by secondary electrons. If these secondary electrons could be removed in an internal cavity of mucosal lined organ, the mucosa will be spared without compromising the target tumor dose. The purpose of this study was to present a RT dose reduction in near target inner-surface (NTIS) of internal cavity, using Lorentz force of magnetic field. Materials and Methods: Tissue equivalent phantoms, composed with a cylinder shaped internal cavity, and adjacent a target tumor part, were developed. The phantoms were irradiated using 6 MV photon beam, with or without 0.3 T of perpendicular magnetic field. Two experimental models were developed: single beam model (SBM) to analyze central axis dose distributions and multiple beam model (MBM) to simulate a clinical case of prostate cancer with rectum. RT dose of NTIS of internal cavity and target tumor area (TTA) were measured. Results: With magnetic field applied, bending effect of dose distribution was visualized. The depth dose distribution of SBM showed 28.1% dose reduction of NTIS and little difference in dose of TTA with magnetic field. In MBM, cross-sectional dose of NTIS was reduced by 33.1% with magnetic field, while TTA dose were the same, irrespective of magnetic field. Conclusion: RT dose of mucosal lined organ, located near treatment target, could be modulated by perpendicular magnetic field.

Radiated disturbance characteristics of SiC MOSFET module

Huang, Huazhen,Wang, Ningyan,Wu, Jialing,Lu, Tiebing The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.2

Wide band gap semiconductor device silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs) have many advantages and are considered to be the most promising alternative to silicon (Si) insulated gate bipolar transistors (IGBTs) in low-/medium-voltage fields. However, a faster switching speed results in more serious electromagnetic disturbance problems in the application of SiC MOSFET. In this paper, an experiment system is established to measure the radiated disturbance of a single SiC MOSFET module operating at 9 kHz-300 MHz. The radiated electric fields of the SiC MOSFET module are mainly concentrated within 160 MHz. The switching voltage and radiated disturbance of the Si IGBT module are measured and compared with those of the SiC MOSFET module. The voltage of the SiC MOSFET has a faster change rate and a higher overshoot, which results in the radiated electric fields of SiC MOSFET module being 5-10 dB higher than those of the Si IGBT module below 8 MHz. The measurement results in the time-domain and frequency-domain correspond. A detailed model of a SiC MOSFET module is established and the radiated electric fields are calculated using the method of moments (MOM). The calculated results show the effectiveness of the model for radiated disturbance prediction. In this paper, the radiated electric fields of a SiC MOSFET module are measured and analyzed, and the calculation model can be used to further evaluate the radiated disturbance characteristics of SiC MOSFET and influencing factors.

Thermal field of large-diameter concrete filled steel tubular members under solar radiation

Daigeng Yang,Guorong Chen,Xiaofei Ding,Juncai Xu 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.26 No.4

Concrete-filled steel tubular (CFST) members have been widely used in engineering, and their tube diameters have become larger and larger. But there is no research on the thermal field of large-diameter CFST structure. These studies focused on the thermal field of the large-diameter CFST structure under solar radiation. The environmental factors and the actual placement position were considered, and the finite element model (FEM) of the thermal field of CFST members under solar radiation (SR) was established. Then the FEM was verified by practical experiments. The most unfavorable temperature gradient model in the cross-section was proposed. The testing results showed that the temperature field of the large-diameter CFST member section was non-linearly distributed due to the influence of SR. The temperature field results of CFST members with different pipe diameters indicated that the larger the core concrete diameter was, the slower the central temperature changed, and there was a significant temperature difference between the center and the boundary. Based on the numerical model, the most unfavorable temperature gradient model in the section was proposed. The model showed that the temperature difference around the center of the circle is small, and the boundary temperature difference is significant. The maximum temperature difference is 15.22°C, which appeared in the southern boundary area of the specimen. Therefore, it is necessary to consider the influence of SR on the thermal field of the member for large-diameter CFST members in actual engineering, which causes a large temperature gradient in the member.

An experimental study on laminar CH4/O2/N2 premixed flamesunder an electric field

Eugene V. Vega,이기용 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.2

This work investigates the electric field effect on gas temperature, radiative heat flux and flame speed of premixed CH4/O2/N2 flames in order to gain a better insight into the mechanism of controlling the combustion process by electro-physical means. Experiments were performed on laminar Bunsen flames (Re<2200) of lean to rich mixture composition ( =0.8-1.2) with slight oxygen enrichment (Ω=0.21-0.30). The Schlieren flame angle technique was used to determine the flame speed, and thermocouple measurements at the post flame gas were conducted. The radiative heat flux was measured by using a heat flux meter. At high field strengths, coincident with the appearance and enhancement of flame surface curvatures, an apparent change in flame speed and gas temperature was observed. However, the application of an electric field had no significant effect on flame speed and temperature when the flame geometry was unaltered. This was supported by radiative heat flux showing negligible electric field effects. The modification in flame temperature and flame speed under electric field was attributed to the field-induced flame stretch due to the body forces produced by the ionic winds. This additional flame stretch, coupled with the influence of non-unity Lewis number, accounts for such changes. This reinforces the idea that the action of an electric field on flames with a geometry that remains practically undeformed produces very minimal effect on flame speed, temperature and radiative heat flux. A possible mechanism of combustion control by the application of flame stretch using electric field was introduced.

Proposing a Low-Frequency Radiated Magnetic Field Susceptibility (RS101) Test Exemption Criterion for NPPs

민문기,이재기,이광현,이동일 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.4

When the equipment which is related to safety or important to power production is installed in nuclearpower plant units (NPPs), verification of equipment Electromagnetic Susceptibility (EMS) must be performed. The low-frequency radiated magnetic field susceptibility (RS101) test is one of the EMS testsspecified in U.S NRC (Nuclear Regulatory Commission) Regulatory Guide (RG) 1.180 revision 1. The RS101test verifies the ability of equipment installed in close proximity to sources of large radiated magneticfields to withstand them. However, RG 1.180 revision 1 allows for an exemption of the low-frequencyradiated magnetic susceptibility (RS101) test if the safetyerelated equipment will not be installed inareas with strong sources of magnetic fields. There is no specific exemption criterion in RG 1.180 revision1. EPRI TR-102323 revision 4 specifically provides a guide that the low-frequency radiated magnetic fieldsusceptibility (RS101) test can be conservatively exempted for equipment installed at least 1 m awayfrom the sources of large magnetic fields (>300 A/m). But there is no exemption criterion for equipmentinstalled within 1 m of the sources of smaller magnetic fields (<300 A/m). Since some types of equipmentradiating magnetic flux are often installed near safety related equipment in an electrical equipmentroom (EER) and main control room (MCR), the RS101 test exemption criterion needs to be reasonablydefined for the cases of installation within 1 m. There is also insufficient data regarding the strength ofmagnetic fields that can be used in NPPs. In order to ensure confidence in the RS101 test exemptioncriterion, we measured the strength of low-frequency radiated magnetic fields by distance. This study isexpected to provide an insight into the RS101 test exemption criterion that meets the RG 1.180 revision 1. It also provides a margin analysis that can be used to mitigate the influence of low-frequency radiatedmagnetic field sources in NPPs

대학생의 방사선의 지식 및 인식 조사 - 방사선 비전공자를 대상으로 -

강연희(Yeon-Hee Kang),박철우(Cheolwoo Park) 한국방사선학회 2019 한국방사선학회 논문지 Vol.13 No.2

본 연구는 방사선 비전공 대학생들을 대상으로 방사선사용에 관한 지식 및 인식을 분석하고자 설문조사를 실시하였다. 회수된 설문을 바탕으로 빈도, 평균과 표준편차, t-test, one-way ANOVA를 사용하였다. 그결과, 방사선의 기본 지식과 사용 분야에 관한 지식 정도는 성별과 연령에서 집단 간 큰 차이는 나타나지 않았다. 전공 계열에서는 일부 항목에서 통계적 차이가 나타났다. 또한 방사선에 대한 인식에서는 여자와 25세 미만에서 더 부정적인 것으로 나타났다(p<0.05). 하부 요인 간 상관관계 분석 결과 방사선 지식이 높을수록 사용 분야의 지식과 방사선사용 인식이 높게 나타났다. 대학생들은 앞으로 사회에 진출하여 방사선 인식을 제고 하는데 영향력이 크다는 점에서 방사선에 대한 올바른 인식이 전달된다면 방사선 산업 발전에 기여하는 긍정적 효과를 나타낼 것으로 판단된다. The purpose of this study was to investigate the knowledge and awareness about radiation use among non -radiation undergraduates. This analysis were used based on the collected questionnaires with Frequency, mean and standard deviation, t-test, one-way ANOVA. As a result, there was no significant difference between the groups in terms of gender and age. There were statistical differences in some items in the major field. In addition, the perception of radiation was more negative in women and under 25 years of age (p<0.05). The correlations between the sub - factors showed that the higher the knowledge of radiation, the higher the perception of knowledge and use of radiation. It is believed that university students will have a positive effect of contributing to the development of the radiation industry if they have a correct understanding of radiation because they are more likely to contribute to public opinion by advancing into society.

시간 경과에 따른 자기장 노출 유·무 환경에서 열형광선량계의 글로우 곡선 및 피폭 방사선량 분석

이재헌(Jae-Heon Lee),고성진(Seong-Jin Ko),김정훈(Jung-Hoon Kim) 한국콘텐츠학회 2016 한국콘텐츠학회논문지 Vol.16 No.8

본 연구는 PET-MRI를 다루는 방사선 작업 종사자들의 효과적인 피폭관리와 경과시간(24시간, 1주, 2주, 3주, 4주) 및 자기장에 따른 개인피폭선량계의 변화를 분석하고자 하였다. 그룹화된 TLD에 열처리 수행 및 방사선을 조사하여 각기 다른 노출 환경에 보관한 후 실험이 종료되면 판독을 수행하여 글로우 곡선 및 피폭 방사선량의 변화 추이를 관찰하였다. 그 결과, 24시간 경과한 TLD 그룹에서 글로우 곡선 및 방사선량의 차이가 있는 것으로 확인되었다. 이는 자기장 노출로 인한 변화인 것으로 해석할 수 있다. 또한 자기장에 노출되지 않은 TLD 그룹의 평균 피폭 방사선량은 15.41 mSv로 나타났으며, 자기장에 노출된 TLD그룹의 평균 피폭 방사선량은 14.83 mSv로 나머지 그룹보다 가장 크게 감소(3.80%)하는 경향을 나타냈다. PET-MRI실에서 근무하는 방사선 작업 종사자가 개인피폭선량계로 TLD를 사용하는 경우, 정기 판독주기에 맞게 TLD 판독 시 자기장 노출로 인한 실제 피폭 방사선량과의 차이는 크게 없을 것으로 판단되어지나 정기 판독이 아닌 중간 판독을 수행하였을 경우, 실제 피폭 방사선량보다 낮은 피폭선량 값을 나타낼 것이다. 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.

국내 방사선종사자 피폭 분류체계 개선에 관한 연구

박수희,한지영,김용민 한국방사선학회 2023 한국방사선학회 논문지 Vol.17 No.2

Occupational exposure records are subject of global interest, and analysis of radiation workers in work categories is being conducted. In Rep. of Korea, according to relevant ministries, the MOHW(Ministry of Health and Welfare), the MAFRA(Ministry of Agriculture, Food and Rural Affairs), and the NSSC(Nuclear Safety and Security Commission) collect and analyze records of occupational exposure by dividing them into 11 work categories. However, this classification system lacks consistency with the systems of major countries, including the UNSCEAR(United Nations Scientific Committee on the Effects of Atomic Radiation). The domestic radiation work field classification system does not have clear classification criteria and does not reflect the characteristics of the radiation work field. Through the analysis of the classification system of the UNSCEAR, we suggested the five main categories(nuclear cycle, medical, industrial, others(education/research, military/public) field and several sub-categories according to each radiation work field. 전 세계적으로 방사선종사자들의 피폭 기록은 관심의 대상이며 피폭이 일어나는 분야에 대한 분석이 수행되고 있다. 한국에서는 유관부처에 따라 보건복지부, 농림축산식품부, 원자력안전위원회에서 종사자들의 피폭을 11개 업종으로 나누어 기록을 수집 분석하고 있다. 그러나 이러한 분류 체계는 유엔방사선영향과학위원회를 비롯한 주요 국가들의 분류 체계와는 정합성이 부족하다. 국내의 종사자 피폭 분류 체계는 명확한 분류 기준이 없고 업종 특성 등을 반영해주지 못하고 있다. 유엔방사선영향과학위원회의 분류 체계를 바탕으로 국내의 분류 체계를 핵주기 분야, 의료분야, 산업분야, 그 외 분야(교육/연구, 군사/공공)의 5개 대분류 체계와 그에 따른 세 분류 및 직군 분류를 본 연구를 통해 제안하였다.