탄소중립을 달성하기 위해 이산화탄소를 포집, 활용, 저장하는 CCUS (carbon capture, utilization, and storage) 기 술이 주목받고 있다. 본 연구에서는 광물 탄산화 공정을 통해 이산화탄소를 탄산염으로 고정하고, 이를 전이금속 탄산염 기반 리튬이온배터리 (LIB) 음극재로 적용하였다. CO2를 탄산염으로 고정후, 이를 이용해 FeCO3를 제작하고, rGO와 PVP와 복합 화하여 음극활물질에 적용하였다. rGO는 전기전도도를 높이고 입자의 응집을 방지해 부피 팽창을 완화했으며, PVP는 계면 활성제로서 입자 표면을 안정화하여 구조적 안정성을 강화하였다. FeCO3-PVP-rGO 복합체 기반한 음극재에 대한 전기화학 테스트를 진행한 결과, FeCO3/rGO 복합체는 1,620 mA/g의 전류 밀도에서 50 사이클 이후에도 400 mAh/g의 용량을 유지하 였다. 본 연구는 CO2를 고부가가치 배터리 소재로 전환하여 차세대 에너지 저장 기술에 기여할 가능성을 시사한다.
Artificial photosynthesis harnesses clean and sustainable solar power to catalyze the conversion of CO2 and H2O molecules into valuable chemicals and O2. This sustainable approach combines energy conversion with environmental pollution control. Non-oxide photocatalysts with broad visible-light absorption and suitable band structures, hold immense potential for CO2 conversion. Nevertheless, they still face numerous challenges in practical applications, particularly in CO2 conversion with H2O. Surface modification and functionalization play the significant role in improving the activity of non-oxide photocatalysts. Multifarious strategies, such as cocatalyst loading, surface regulation, doping engineering, and heterostructure construction, have been explored to optimize light harvesting, bandgap driving force, electron–hole pairs separation/transfer, CO2 adsorption, activation, and catalysis processes. This review summarizes recent progress in surface modification strategies for non-oxide photocatalysts and discusses their enhancement mechanisms for efficient CO2 conversion. These insights are expected to guide the design of high-performance non-oxide photocatalyst systems.
As nuclear decommissioning ventures become increasingly complex, the role of digitalization in facilitating and enhancing these operations is becoming indispensable. This transition to a more digitized approach presents a myriad of advantages, including: augmented avenues for data acquisition, analysis, and visualization to bolster dismantling strategies; simulations in virtual environments for operator training; precise forecasting of future waste emergence, culminating in refined cost estimations; and more immersive decommissioning visualizations for both operators and external stakeholders. Salient benefits conferred by the integration of digital technologies in decommissioning encompass improved collaboration, enriched knowledge transfer, clarity regarding present technological constraints, insights into key influencing factors, clearer criteria for technology selection, and a profound understanding of the potential challenges and merits of a broader incorporation of digital tools in decommissioning endeavors. Of paramount importance is the opportunity presented for superior workforce training and safety measures, exemplified by ALARAbased planning. Amidst the myriad facets of digital adoption, 3D modeling of nuclear facilities derived from laser-scanned point clouds stands out as a pivotal domain in the digitalization. The transformation of intricate point cloud data into a comprehensible 3D mesh remains the crux of this paper. The process of mesh generation, despite being simpler than its counterpart of converting to a 3D solid model, is crucial for multiple reasons. The resultant 3D mesh offers an enhanced visual representation compared to a sparse point cloud, paving the way for improved spatial perception. Furthermore, it serves as a rudimentary tool for approximating component volumes and the ensuing waste, thereby playing an instrumental role in waste manipulation strategies, notably in collision detection. This paper delves deep into the nuances of mesh generation, conducting an parametric study of mesh conversion algorithms, including down-sampling rates. Through this rigorous examination, we endeavor to shed light on optimal methodologies, hoping to catalyze advancements in the digitalization of nuclear decommissioning processes.
Developing the high-performance semiconductor photocatalytic materials is an eternal topic under the background of the current energy and environment requirements. In recent years, single-atom photocatalysts (SAPCs) have been brought a lot of attention in energy conversion and environmental purification because of their unique characteristics and properties, including the unique coordination patterns, outstanding atomic utilization, quantum confinement effects, high catalytic activity, etc. Hence, this critical review focuses on the summarized various synthetic methods and the recent important applications of SAPCs, including photocatalytic H2 evolution (PHE) from water splitting, photocatalytic CO2 reduction, photodegradation of organic pollutants, etc. The prospects and challenges for future research topics of SAPCs with excellent activity and stability for various photocatalytic applications are prospected at the end of this review. We sincerely expect that this critical review can promote deep-level insight into the SAPCs subject for the future significant applications in other fields.
Since 2018, Central Research Institute of Korea Hydro & Nuclear Power (KHNP–CRI) has been operating an X-ray irradiation system with a maximum voltage of 160 kV and 320 kV X-ray tube to test personal dosimeters in accordance with ANSI N13.11-2009 “Personnel Dosimetry Performance- Criteria for Testing”. This standard requires that dosimeters for the photon category testing be irradiated with the X-ray beams appropriate to the ISO beam quality requirements. KHNP-CRI has implemented the fourteen X-ray reference radiation beams in compliance with ISO-4037-1, 2, and 3. When installing the X-ray irradiation system, KHNP-CRI evaluated the uncertainties of dose conversion coefficients for deep and shallow doses, based on “Catalogue of X-ray spectra and their characteristic data – ISO and DIN radiation qualities, therapy and diagnostic radiation qualities, unfiltered X-ray spectra” published by Physikalisch Technische Bundesanstalt (PTB). A CdTe detector (X-123, AMPTEK) with disk type collimators made of tungsten was used to acquire X-ray spectra. The detector was located at 1 m from the center of the target material in the Xray tubes. Six uncertainty factors for the dose conversion coefficients for the fourteen X-ray beams were chosen as follows; the minimum and maximum cut-off energies Emin and Emax, the air density (ρ), the accuracy of the high-voltage of the X-ray tube, statistics of the pulse height spectra and the unfolding method. For example, uncertainty of each quantity for a HK30 beam was calculated to be 0.3%, 2.32%, 0.19%, 1.25%, and 0.13%, and 0.18%, respectively. The combined standard uncertainty for the deep dose conversion coefficient of the HK30 beam was calculated to be 2.67%. The coverage factor corresponding to a 95 percent confidence interval was obtained as k = 1.8 using a Monte Carlo method, which is slightly lower the coverage factor of k = 1.95 for a Gaussian distribution. This seems to result from that two dominant uncertainties, the unfolding uncertainty and minimum cut-off energy uncertainty, follow a rectangular distribution.
About 83% of the information systems of administrative and public agencies are operated by agencies, and most of them are vulnerable to security due to the small scale of operation, insufficient facilities, and lack of dedicated personnel. To address these issues, the Ministry of the Interior and Safety announced in June 2021 that, as part of the “Second Basic Plan for E-Government,” all information systems of administrative and public agencies will be converted to a cloud-based integrated management operating environment by 2025 to provide stable public services. Accordingly, relevant laws and guidelines should be researched and analyzed to prepare for the cloud conversion of the Nuclear Export and Import Control System (NEPS) operated by the Export and Import Control Office of the Korea Institute of Nuclear Nonproliferation and Control (KINAC). The Cloud Computing Act defines cloud computing, establishes a basic plan and implementation plan, provides support for promoting the adoption of cloud computing by state institutions, supports the construction of integrated information and communication facilities based on cloud computing technology, provides cost and technical support, and regulates cloud security certification, and applies the Personal Information Protection Act and the Act on Promotion of Information and Communication Network Utilization and Information Protection to protect personal information. The E-Government Act defines integrated standards and principles for information resources, support for the use of cloud computing services, classification standards for information resources, and integrated standards for calculating the size and capacity of information systems. The Notice on Standards for Using Cloud Computing Services and Securing Safety for Administrative Agencies and Public Institutions specifies the standards for using cloud computing services and measures to secure stability for administrative agencies, contracts for using cloud computing services, and ensuring continuity of cloud computing services. The Basic Guidelines on National Information Security stipulate the establishment and implementation of security measures, system security, user security, security management, information and communication network security separating internal network and internet network, and cloud computing security measures, and stipulate the NIS security review when introducing private cloud services. In order to convert NEPS to the cloud computing services, network, and software design plans, transfer plans, and cloud operation plans will be established in compliance with the relevant laws and guidelines. And future research will include researching the system status of major public and private cloud service providers and analyzing their advantages and disadvantages.
본 연구는 코팅 방법을 활용한 단결정 양극 소재 연구로서 Ni-rich계 다결정 양극 소재로 부터 단결정 양극 소재를 합 성하여 사이클 구동 시 양극 소재의 안정성을 향상시키고자 한다. 양극 소재에 LixCoO2와 LixSnO3 를 각각 코팅하여 이차입자 내부 혹은 외부에 코팅층이 형성된 양극 소재를 합성한 후 이를 소결하여 단결정 형성에 대한 영향을 비교 하였다. 입자 외부에 LixSnO3가 코팅되어 열처리 된 Ni0.8Co0.1Mn0.1O2(NCM811)의 경우 코팅 처리 없이 열처리된 양극 소재 보다 개선된 수명특성을 보였으나, 단결정화가 이뤄지지 않았다. 입자 내부에 LixCoO2 코팅층이 형성된 NCM811 을 열처리 한 결과 이차입자 내부에 형성된 Co 코팅층이 결정화되어 50회 사이클 후 기준 단결정 양극 소재의 방전용 량인 117.34 mAh·g-1 대비 129.11 mAh·g-1의 높은 방전용량을 나타내었고, 형상제어를 통해 이성적인 단결정화가 이뤄 졌다. 본 연구는 다결정체인 Ni-rich 양극소재의 단결정화에 대한 유요한 통찰력을 제공할 것으로 예상한다.
Coal tar pitch is a product with high carbon content and aromatic compounds. Modified coal tar pitch is a high quality raw material for the preparation of intermediate phase pitch, needle coke, carbon microspheres, et al. In this paper, modified coal tar pitch was used as raw material, nitrogen was used as protective gas, and thermal conversion was carried out at constant temperatures (370, 390, 410, 420 °C). Polarized light microscopy, SEM, elemental analysis, FTIR spectroscopy, Raman spectroscopy and XRD diffraction combined with split-peak fitting were used to characterize the microstructures of the thermal transformation products. The results showed that the Iar and CH3/ CH2 contents of the products increased with the gradual increase of the thermal conversion temperature, and the aromatic content increased. And the higher the temperature at the same heating rate, the more the ideal graphite microcrystal content, and the defective graphite microcrystals are converted into ideal graphite microcrystals during the thermal conversion process. When the reaction temperature exceeds 390 °C, the microstructure of the thermal transformation products is anisotropic spheres, and the small spheres fuse with each other and tend to be basin-like and mosaic structure as the temperature increases.
스마트농업의 활성화를 위해서는 농업환경 데이터의 관측과 모델 그리고 통계자료의 상호운영성 확보가 중요하므로, 이를 위한 격자체계의 적용방안을 탐색하고자 한다. 국내외 격자체계 표준에 대한 사례조사와 농업분야의 격자표준 적용사례조사를 벤치마킹하고 국립농업과학원과 상위기관의 표준현황을 살펴보고, 농업환경 공간정보의 목록과 분류체계를 구축한 후, 사용자 요구사항을 파악하기 위한 설문을 실시하여 적정한 격자 크기를 선정하였다. 농업환경 공간정보의 공유와 활용을 위하여 국토지리 정보원의 기관표준을 차용하여 군 이하 소규모 지역은 10m, 광역시・도는 100m, 농촌경관 목적으로는 500m, 전국은 1km 격자 크기로 안을 제시하였고 원활한 표준 적용을 위한 전략을 제안하고, 현장 조사 및 관측 결과를 격자로 변환할 수 있도록 오픈소스 기반의 변환 툴을 개발하여 격자표준 적용 용이성과 시간 절약성을 확보하였다.
Dose-rate monitoring instruments are indispensable to protect workers from the potential risk of radiation exposure, and are commonly calibrated in terms of the ambient dose equivalent (H*(10)), an operational quantity that is widely used for area monitoring. Plastic scintillation detectors are ideal equipment for dosimetry because of their advantages of low cost and tissue equivalence. However, these detectors are rarely used owing to the characteristics caused by low-atomic-number elements, such as low interaction coefficients and poor gamma-ray spectroscopy. In this study, we calculated the G(E) function to utilize a plastic scintillation detector in spectroscopic dosimetry applications. Numerous spectra with arbitrary energies of gamma rays and their H*(10) were calculated using Monte Carlo simulations and were used to obtain the G(E) function. We acquired three different types of G(E) functions using the least-square and first-order methods. The performances of the G(E) functions were compared with one another, including the conventional total counting method. The performance was evaluated using 133Ba, 137Cs, 152Eu, and 60Co radioisotopes in terms of the mean absolute percentage error between the predicted and true H*(10) values. In addition, we confirmed that the dose-rate prediction errors were within acceptable uncertainty ranges and that the energy responses to 137Cs of the G(E) function satisfied the criteria recommended by the International Commission.
Radiation workers receive exposure during radiation works such as decontamination or cutting of metals and concrete in decommissioning nuclear power plants. To reduce occupational exposure, various radiation protection measures should be prepared by estimating the exposure dose in advance. RESRAD-RECYCLE, the computer code, is generally used for estimating occupational dose due to handling metals contaminated with radioactive materials. However, RESRAD-RECYCLE used the dose conversion factors (DCF) of EPA FGR No. 11 based on ICRP Publications 30 and 48 published in the 1980s for internal exposure estimation. This study compared the DCFs of RESRAD-RECYCLE with those of the relatively recently published ICRP Publications 119 and 141. In addition, the internal exposure dose was evaluated by changing the value of the DCFs of RESRAD-RECYCLE. As a result of the comparison, ICRP Publication 119 showed that the DCF values of most nuclides were significantly lowered. On the other hand, in the case of nuclides emitting gamma rays, there was generally no significant change in the value of DCFs. In addition, in the case of 65Zn and 94Nb, the DCF increased compared to the previous ICRP publications. The exposure dose of the decommissioning workers of Hanul Units 1 and 3 and Hanbit Unit 4 was also calculated in this study. The expected radioactivity concentration of the steam generator chamber of each unit was used as the source term. The concentration of metal dust in the air generated during cutting was calculated and applied to evaluate the internal exposure dose. As a result of the dose evaluation, there was a difference in exposure dose up to 0.2 mSv in the scrap cutter scenario of Hanbit Unit 4, which generated a lot of dust and had a high radioactivity concentration. On the other hand, in the case of the slag worker, there was no difference in the dose because the working time was very short, and the inhalation of metal dust was small, even if the latest DCF was applied.