Accurate 3D Human Pose Estimation (3DHPE) is necessary for computational dosimetry of workers near radioactive sources, but existing frameworks have difficulty dealing with single-view configuration due to heavily occluded environments in multiple camera views. Here, a 3DHPE framework is proposed that utilizes a single RGB-D (Red, Green, Blue, and Depth) camera. First, 3D poses relative to the body root are estimated by employing ground plane detection, after which the position of the body root is determined by matching key points of the 3D pose within a voxelized point cloud reconstructed from depth images. In experiments, the proposed framework achieved a 22.7 % reduction in the mean per joint position error and a 29.2 % error reduction for the wrists when applied to a challenging dataset featuring substantial occlusions from interventional radiology equipment and other workers. The proposed framework demonstrated comparable positioning accuracy as state-of-the-art techniques without requiring the collection of actual 3D pose data. It can be utilized as a supplementary tool for reducing uncertainty in computational dosimetry and optimizing the workflow in medical settings.

회전익 드론(Rotary-wing drone)은 제자리비행(Hovering)이 가능하기 때문에 다양한 산업분야에 활용되고 있다. 하지만 회전익드론은 에너지 효율이 좋지 않으며, 이러한 문제점을 해결하기 위해 무인 드론스테이션(Drone-station)이 개발되고 있다. 본 논문은 드론 순환임무 시스템을 구현하고 기능을 검증하였다. 드론 순환임무 시스템은 다수의 드론과 무인 드론스테이션, 그리고 관제시스템으로 구성된다. 본 논문은 자율비행 드론, 자동 배터리 교체식 드론스테이션, 그리고 관제시스템을 실제로 제작하였으며, 드론 순환임무 시스템의 검증을 위해 드론과 드론스테이션을 대신할 수 있는 더미(Dummy) 프로그램을 함께 개발하였다. 본 논문은 제작된 실제 드론 및 드론스테이션, 그리고 더미 드론 및 드론스테이션을 이용하여 드론들의 임무중단 및 임무재개 상황을 모의실험 하였다. 실험결과, 드론 순환임무 시스템의 드론들은 끊임없이 비행이 연속되는 것을 확인했다.

PuO2(cr) dissolution in natural water was investigated at 25°C and 60°C under atmospheric conditions. The concentration of Pu in solutions [Pu], was monitored for 1 year of reaction time. PuO2(cr) dissolution in natural water reached a steady state within 2 months at 25°C. The [Pu] in groundwater and seawater at pH 8 were in the range of [Pu] = 0.9–34 and 3.4–27 nM, respectively. The [Pu] in concrete porewater (rainwater equilibrated with concrete) at pH 8.1–10.9 was in the range of 0.1–3.2 nM. The [Pu] and pH values of groundwater were similar to those of seawater samples having a high ionic strength. The measured [Pu] at equilibrium in all samples was higher than the calculated solubility curves for PuO2(am, hyd). Experimental evidence is insufficient to confirm the oxidation state of Pu in solution and solid phases. However, the results of geochemical modeling indicate that PuO2(am, hyd) and aqueous Pu(IV) species are dominant in natural water samples of this work. The dissolution behavior of PuO2(cr) in natural waters is comparable to the oxidative dissolution of PuO2(am, hyd) in the presence of PuO2(coll, hyd). The dissolution of PuO2 in groundwater decreased at higher temperatures, whereas the influence of temperature in seawater and porewater was not significant under these experimental conditions.

Most vision-based landing algorithms cannot be applied in a severe vision-detection environment. However, the application of a deep learning technique to vision-based landing algorithm can solve the problem of a severe vision-detection environment, especially in vision-impaired environments. Based on this fact, a novel-landing concept with deep learning technique is proposed in this study. Three main techniques applied for guided landing are 1) deep learning for accurate landing mark detection; 2) location-memorized system for coping temporal failure of the landing mark detection; 3) Unmanned Aerial Vehicle control algorithm for vibration minimization in vision sensor. The proposed system successfully and accurately guided the multicopter onto the landing area without failure in vision-impaired environments. The results show that the proposed landing algorithm can overcome environmental restrictions in operating multicopters.

산림지역은 다양한 지형, 장애물 등의 요인에 따라 산불 발생 시에 비가시권에서 드론의 수동 조작을 통한 화재진압은 상당히 어렵다. 특히, 야간의 경우 안전상의 이유로 헬기 등의 항공지원이 불가능하며, 사람 또한 접근이 어려워 드론을 통한 화재진압의 필요성이 점차 커지고 있다. 본 연구에서는 비전문가도 쉽게 드론을 산불진압에 활용할 수 있는 드론 제어 기술을 제안하였다. 제안된 기술은 영상-열화상 이미지 정보 기반의 딥러닝을 활용하여 사용자가 지정한 화재원점을 지속적으로 추적하며, 화재원점으로 유도 비행을 수행한다. 유도비행 시, 충돌 회피 기능이 적용되었다. 또한, 유도기술은 영상기반 정밀착륙에 동시 적용되어 딥러닝으로 인한 임무 컴퓨터에서의 메모리 소모를 최소화하였다. 본 연구는 산불진압용 드론에 직접 활용될 수 있을 것으로 기대되며, 향후 사용자 친화적 드론 제어 시스템의 기술로 활용될 수 있을 것으로 기대된다.

Mechanism and kinetics of Rhenium complexes as a surrogate of Technetium-99 (Tc-99) is worthy of study from radioactive waste safe disposal perspective. Re(IV)-EDTA was synthesized via the reduction of Re(VII) with Sn(II) in the presence of Ethylenediaminetetraacetic acid (EDTA). The Re(IV)-EDTA was then degraded by H2O2 (7%-30%) at pH of 3-11 in ionic strength I = 0-2 M solution. The Re-EDTA was observed to degrade more rapidly at pH of <= 3-4 than one of >= 10-11 and remained stable at pH = 7-9. The Re-EDTA was degraded in accordance with the Fl(+) addition mechanism in the acidic range and ligand charge transfer in the alkaline region. Complex degradation followed the zero-order rate kinetics for the H+ and Re-EDTA parameters, apart from a pH of 3, for which degradation was a better fit to first order kinetics. A higher Re(IV)-EDTA stability at a pH of 7-9 demonstrated that Re(IV)-EDTA (or Tc-99(IV)-EDTA) tends to be more persistent in natural environments similar to the pH range of 7-9. (C) 2022 The Author(s). Published by Elsevier B.V.

The uptake of beryllium by hardened cement paste (HCP, with CEM I 42,5 N BV/SR/LA type) in degradation stage I was investigated with a series of batch sorption experiments with 10−6 M ≤ [Be(II)]0 ≤ 10−2.5 M and 2 g·L−1 ≤ [S/L] ≤ 50 g·L−1. All experiments were performed under Ar atmosphere at T = (22 ± 2) °C. Solubility limits calculated for α-Be(OH)2(cr) in the conditions of the cement pore water were used to define the experimental window in the sorption experiments. Beryllium sorbs strongly on HCP under all of the investigated conditions, with log Rd ≈ 5.5 (Rd in L⋅kg−1). Sorption isotherms show a linear behavior with a slope of ≈+1 (log [Be(II)]solid vs. log [Be(II)]aq) over four orders of magnitude (10−8 M ≤ [Be(II)]aq ≤ 10−4 M), which confirm that the uptake is controlled by sorption processes and that solubility phenomena do not play any role within the considered boundary conditions. The similar uptake observed for beryllium in calcium silicate hydrate (C-S-H) phases supports that the C-S-H phases are the main sink of Be(II) in cement. The strong uptake observed for Be(II) agrees with the findings reported for heavier metal ions, e.g., Zn(II), Eu(III), Am(III), or Th(IV). The exceptional sorption properties of beryllium can be partially explained by its small size, which result in a charge-to-size ratio (z/d) of the same order as Eu(III) or Am(III). Kinetic experiments confirm the slow uptake of Be(II), which is characterized by a two-step process. In analogy to other strongly sorbing metal ions such as Zn(II) or Th(IV), a fast surface complexation (t < 4 days) followed by a slower incorporation of Be(II) in the C-S-H structure (t ≥ 60 days) are proposed. The surface complexation was studied in detail with molecular dynamic simulations, and the most common surface species are identified and described. This work provides the first experimental evidence supporting the strong uptake of Be(II) by HCP in degradation stage I, further extending previous findings on C-S-H phases and HCP in degradation stage II. These results overcome previous conservative estimates assuming no or only a weak uptake in cementitious systems and represent a relevant contribution for the quantitative assessment on the retention/mobilization of beryllium in the context of nuclear waste disposal.

일반적으로 산불진화용 무인기는 사람의 원격 조종에 의해 운영되고 있으나, 산불의 특성상 다수 지점의 화재진압 및 통신이 원활하지 않는 산림환경에서는 활용이 어렵다. 이에 무인기를 이용하여 산불진압 임무를 수행하기 위해서는 진화지점의 자동 예측을 통한 무인기 완전 자동화가 필요하다. 본 연구에서는 딥러닝 기술 중 하나인 Semantic Segmentation 기술을 이용하여 소화탄 투화지점 예측 알고리즘을 제안하였다. 제안된 방법을 통하여 기계학습에 사용되지 않은 독립 데이터를 통한 화재 지점 국지화 및 소화탄 투하지점의 추천 평가를 수행하였으며, 90% 이상의 정확도로 소화탄 투하 필요 지점을 예측하였다. 본 연구에서 개발된 방법은 향후 무인기를 이용한 화재진압 완전 자동화를 위해 활용될 수 있을 것으로 기대된다.

This study investigates for optimizing thermal treatment conditions for the effective decontamination of cobalt(Co)-contaminated concrete waste. About 21 g of ordinary Portland cement (OPC, Type I), 37 g of dry sand, 5 g of fly ash, and 24 g of aggregates were mixed, cured for 28 days, and used for characterization and thermal treatment. Thermal treatment was conducted at different temperatures between 105 degrees C and 600 degrees C. The samples were characterized using SEM, XRD, FTIR, XRF, and XAS. Up to 600 degrees C, mass loss only occurred for water molecules in the concrete with similar to 60% volume reduction, suggesting an optimum temperature between 500 degrees C and 550 degrees C. During thermal treatment, Co phase changed from Co3O4 to CoO, and among the various chemical solutions, chloric acid exhibits the highest Co decontamination efficiency. The results suggest that a combination of thermal and chemical treatments can enhance Co removal from concrete waste. (C) 2020 Elsevier Ltd. All rights reserved.

Concrete is the main building material of nuclear power plant (NPP) and other nuclear facilities. It is the most common radioactive waste in the decommissioning of NPP along with metal wastes which account for more than 70 % of total solid wastes [1, 2]. Given that the NPP decommissioning in Korea in the future could result in a huge amount of radioactive concrete waste, the optimal treatment for decontaminating concrete waste is required in advance and an efficient development of concrete decontamination technology is necessary.

Relative permeability is an important attribute influencing subsurface multiphase flow. Characterization of relative permeability is necessary to support activities such as carbon sequestration, geothermal energy production, and oil and gas exploration. Previous research efforts have largely neglected the relative permeability of wellbore cement used to seal well bores where risks of leak are significant. Therefore this study was performed to evaluate fracturing on permeability and relative permeability of wellbore cement. Studies of relative permeability of water and air were conducted using ordinary Portland cement paste cylinders having fracture networks that exhibited a range of permeability values. The measured relative permeability was compared with three models, 1) Corey-curve, often used for modeling relative permeability in porous media, 2) X-curve, commonly used to represent relative permeability of fractures, and 3) Burdine model based on fitting the Brooks-Corey function to fracture saturation-pressure data inferred from x-ray computed tomography (XCT) derived aperture distribution results. Experimentally-determined aqueous relative permeability was best described by the Burdine model. Though water phase tended to follow the Corey-curve for the simple fracture system while air relative permeability was best described by the X-curve.

Bismuth-functionalized graphene oxide (Bi-GO) was successfully synthesized and showed both high iodide and iodate removal efficiencies from radioactive wastewater. Batch experiments for kinetic and selectivity tests were performed, respectively. Additional SEM, XRD, FT-IR, and XPS analyses were performed for characterization of a sorbent and bismuth on the GO surface and this confirmed that bismuth on the GO surface reacted with iodine species by surface complexation (or precipitation). Dominant surface species are BiOI and Bi(IO3)3 for iodide and iodate removal, respectively. After the selectivity test using a KCl background solution with varying concentrations, Bi-GO still showed higher removal efficiencies (≥95%) for both iodide and iodate than the commercial silver-exchanged zeolite (≥95% for iodide and ≤25% for iodate). Our study suggests the potential application of Bi on graphene-based materials for selective removal of both iodide and iodate from radioactive wastewater.

Batch adsorption, batch diffusion, and flow-through column experiments were conducted using groundwater and fractured rock collected in unsaturated zone to increase our understanding of sorption and transport behavior of radionuclides. Increasing Kd values were observed in the sequence 90Sr, 99Tc, and 3H regardless of the geological media tested. For all sorbing radionuclides, Kd values for the fracture-filling/coating material were observed to be higher than those for without fracture-filling/coating material regardless of the groundwater. These higher Kd values are the result of zeolite mineral in filling/coating material of fractured rock. The batch diffusion and flow-through column experiments were also conducted using the same fractured rock sample, and the results of diffusion and column experiments showed similar trend of radionuclide sorption and transport to sorption experiment. In this study, sorption Kd of radionuclide was determined and used to increase our understanding of radionuclide retardation through fracture-filling/coating materials.