The Korea Research Institute of Standards and Science has developed certified reference materials (concrete, soil, and metal radioactive liquid) for measuring gamma-emitting radionuclides to improve and maintain the quality assurance and quality control of the radioactivity measurement in decommissioning nuclear power plants. The raw materials that make up each CRM were mixed in an appropriate ratio with radionuclides. For certification and homogeneity assessment, 10 bottles were randomly selected, two sub-samples were collected from each bottle, and radionuclides were measured via HPGe gamma spectrometry. The results of the homogeneity tests using a one-way analysis of variance on the radionuclides in the CRMs fulfilled the requirements of ISO Guide 35. Coincidence summing and self-absorption correction were performed on measurement results by introducing the Monte Carlo efficiency transfer code and Monte Carlo N-Particle transport code. In concrete analysis, the reference values for five radionuclides (60Co, 241Am, 134Cs, and 137Cs) in the CRM were in the range of 15-40 Bq/kg, and the expanded uncertainty was within 10% (k = 2). In soil analysis, the reference values for the 137Cs and 60Co were 118.7 and 124.4 Bq/kg, and the expanded uncertainty was within 10% (k = 2). In metal radioactive liquid analysis, the reference values for 134Cs, 137Cs and 60Co in the CRM were in the range of 200-270 Bq/kg, and the expanded uncertainty was within 7% (k = 2).

This study is about the production of radiation sources of simulated concrete and soil reference materials to verify the validity of the quality establishment and measurement of the detector (HPGe) of the radioactive soil and concrete waste classification system, which is being developed to quickly and accurately classify nuclear decommissioning waste. Specific activity of gamma nucleus among radioactive wastes is evaluated using gamma spectroscopy. At this time, in order to verify the validity and reliability of measuring equipment, it shall be a standardized substance of the same medium as nuclear decommissioning waste (chemical ingredients, particles, density, etc.) in order to correct the energy and efficiency of gamma nuclide analysis equipment. The CRM used for the detector’s energy correction used a 1 L Marinelli beaker standard correctional radiation source consisting of 10 radioactive isotopes. In order to correct efficiency, in accordance with the production and certification process of the Korea Standards and Research Institute, it has produced artificial simulated radioactive concrete similar to nuclear decommissioning waste (30% for cement, 60% for regulation and 10% for bentonite). The radioactive homogeneity of the simulated concrete reference materials was evaluated using dispersion analysis (ANOVA) in accordance with ISO Guide 35, while 137Cs and 60Co of concrete reference materials were able to obtain homogeneous measurements both in and between bottles. The self-absorption rate of the simulated concrete reference material was determined by the MCNP computer simulation measurement method, and the self-absorption correction coefficients of 137Cs and 60Co were assessed at 0.995 and 0.996, respectively, and the standard value for the radiation of the simulated concrete reference material was calculated on the weighted average of the measurements of 20 samples. The uncertainty about the reference value was calculated by combining measurement uncertainty (Type B evaluation), bottle to bottle standard deviation, and uncertainty within bottle by modifying the formula suggested in ISO Guide 35. The concentration of 137Cs and 60Co of reference materials was divided into high-speed measurement mode and precision measurement mode in consideration of the self-disposal standard. The reference value and uncertainty of expansion among reference materials for high-speed measurement mode were rated at 1,032.7 ± 64.0 Bq·kg−1and 1,083.7 Bq·kg−1, respectively. The standard value and expansion uncertainty for 137Cs and 60Co among reference materials for precision measurement mode were rated at 113.7 ± 10.0 Bq·kg−1 and 122.3 ± 10.3 Bq·kg−1, respectively.

As Kori-1 permanently shut down in Korea, it is expected that a large amount of radioactive waste will be generated during decommissioning of nuclear power plants. Radioactive concrete waste is contaminated up to depth of 100 mm with radionuclides such as 137Cs and 60Co. The radioactive waste should be accurately classified to reduce the cost of disposing of radioactive waste. Therefore, the specific radioactivity of waste must be precisely evaluated by gamma-ray measurements emitted from the radionuclides. In general, the effectiveness of the radioactivity measurement and process is confirmed using certified reference material (CRM) composed of water or agar. However, the decommissioning waste differs from this CRM in apparent density and chemical elements, so the specific radioactivity is underestimated or overestimated. Therefore, reference material composed of the same apparent density and chemical elements as the sample is required to improve the quality of radioactivity measurement. The purpose of this study is to develop a concrete reference material for the nuclear decommissioning waste. The concrete reference material composed of SiO2, CaO, and Al2O3 were manufactured in compliance with ISO Guide 35. 10 bottles were randomly selected for homogeneity test, and 2 samples for analysis were taken from each bottle. The specific radioactivity was measured using an HPGe detector with an efficiency of 30%. The results of the homogeneity test of 137Cs and 60Co satisfied the requirements of ISO Guide 35. Coincidence summing and selfabsorption effects were corrected using the Monte Carlo efficiency transfer code and Monte Carlo NParticle transport code. The reference values of 137Cs and 60Co in the concrete reference material were evaluated in the range of 1,000–1,100 Bq·kg−1 and extended uncertainty was around 7%.

제품이나 서비스에서 사용자가 예상하지 못한 의외성을 제공할 때 사용자는 만족을 넘어 감동할 수 있으며, 최근 몇몇 애플리케이션이나 웹서비스는 이러한 의외성을 제공하고 있다. 그러나 의외성 자체는 오히려 사용 용이성을 떨어뜨리는 등 문제를 야기 시킬 수 있음에도, 기존 모바일 애플리케이션 관련 연구들은 주로 사용성 중심의 만족을 다루었다. 따라서 본 연구에서는 이러한 의외성으로 인한 사용자 경험의 변화를 세렌디피티(뜻밖의 발견으로부터 유발되는 예상치 못한 즐거움) 개념을 이용하여 모바일 애플리케이션의 UX 분야에서 실험적으로 확인하고, 이로부터 유발되는 요인이 사용자 만족에 미치는 영향에 대해 관찰했다. 즉, 모바일 애플리케이션의 인터랙션을 통해 유발시킨 의외성과 동시에 게임 요소를 제공한 세렌디피티, 지각된 신규성과 지각된 사용 용이성, 지각된 유용성, 그리고 만족 등의 요인들 간 관계를 살펴봤다. 그 결과 세렌디피티가 지각된 신규성에 정(+)의, 사용 용이성에 부(-)의 영향을 미치고, 지각된 신규성과 지각된 사용 용이성이 지각된 유용성에 정(+)의 영향을 미치며, 세 가지 요인 모두 사용자 만족에 정(+)의 영향을 미치는 것이 관찰됐다.

X-선 영상에서 필터를 통한 여과의 역할은 영상 형성에 유용한 광자를 이용해 환자의 피폭량을 낮춤과 동시에 영상의 대조도를 높이는 것이다. 영상을 형성하는 데 있어서 저에너지 X-선은 환자 조직의 최초 몇 cm 부위에서 흡수되고 고에너지 부분만을 통과하여 형성되므로, 방사선 여과는 여과물질을 삽입하여 저에 너지 X-선을 여과물질로 하여금 흡수시켜 환자의 피폭량을 낮추고 영상의 질을 높인다. 본 연구의 목적은 시뮬레이션을 통해 이상적인 환경에서 부가 필터가 방사선 영상 촬영 시 영상의 화질에 미치는 영향을 확 인하고, 실제 방사선 영상을 촬영할 경우와 비교하는 것이다. 이를 위해 시뮬레이션 프로그램인 Geant4 Ap plication for Tomographic Emission (GATE)를 이용해 Polymethylmethacrylate (PMMA) Phantom의 실제 크기, 모양과 재질을 모사하고 부가 필터의 사용유무 및 필터의 두께에 따른 촬영 조건을 설정하여 시뮬레이션 결과 영상을 얻어냈다. 또한, Digital Radiography (DR)장비로 실제 PMMA Phantom을 필터가 없는 경우와 필터가 있을 때 그 두께를 변화시키며 촬영했다. 시뮬레이션의 결과 영상과 실제 실험을 통해 얻은 영상을 각각 Image J 프로그램을 이용해 Contrast-to-noise ratio (CNR) 평가를 실행한 뒤, 시뮬레이션 결과 영상과 최종적으로 도출된 두 영상의 변화 추이를 비교 측정했다. 실험 결과 DR장비와 시뮬레이션 영상 모두 CN R이 감소하는 추세를 보였으며, 이는 결국 영상에서의 대조도 감소로 인해 나타난 결과였다. 이론적으로 관전압 (kVp)이 증가하면 대조도가 감소하고, 이를 통해보았을 때 필터는 저에너지부의 X-선을 흡수하면서 전체적인 선량을 감소시키지만, X-선의 평균에너지를 증가시키는 역할을 한다는 것을 알아볼 수 있었다.