A Study on Solidification of Uranium Contaminated Soil Waste Based on Glass-ceramization

Jaewoong Hwang,Jaseung Koo,Keunyoung Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

The decommissioning of nuclear-related facilities at the end of their design life generates various types of radioactive waste. Therefore, the research on appropriate disposal methods according to the form of radioactive waste is needed. This study is about the solidification of uranium contaminated soils that may occur on the site of nuclear facilities. A large amount of radioactively contaminated soil waste was generated during the decommissioning of the uranium conversion plant in KAERI, and research on the proper disposal of this waste has been actively conducted. Numerous minerals in the soil can become glass-ceramic through the phase change of minerals during the sintering process. This method is effective in reducing the volume of waste and the glassceramic waste form has excellent mechanical strength and leaching resistance. In this study, the optimum temperature and time conditions were established for the production of glass-ceramic sintered body of soil. The compressive strength and leachability of the sintered body made by applying the optimal conditions to simulated waste was confirmed. The basic physicochemical properties of simulated soil waste were identified by measuring the pH, moisture content, density, and organic matter content. The elemental compositions in the soil was confirmed by XRF. Soils were classified by particle size, and each sample was compressed with a pressure of 150 MPa or more to prepare a green body. Based on the TG-DSC analysis, an appropriate heating temperature was set (>1,000°C), and the green body was maintained in a muffle furnace for 2~6 hours. The optimal sintering conditions were selected by measuring the compressive strength and volume reduction efficiency of the sintered body for each condition. The difference between the green body and sintered body was observed by XRD and SEM. In the experiments for evaluation of additives, the selected chemical substances were mixed with the soil sample in a rotator. Based on the results of TG-DSC, sintered body was made at 850°C, and the compressive strength and volume reduction were compared. Based on the results, the most effective additive was determined, and the appropriate ratio of the additive was found by adjusting the range of 1~5 wt%. This study was confirmed that the sintered soil waste showed sufficient stability to meet the disposal criteria and effective volume reduction for final disposal.

Study on the Basic Properties of Sintering for Treatment of Uranium Contaminated Soil

Jaewoong Hwang,Keunyoung Lee,Jaseung Koo 한국방사성폐기물학회 2021 한국방사성폐기물학회 학술논문요약집 Vol.2021 No.06

Effect of Additives for the Stabilization of Radioactive Soil Waste by Glass Composite Materials

Jaewoong Hwang,Keunyoung Lee,Jaseung Koo 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

As the design life of nuclear power plants are coming to the end, starting with Kori unit 1, nuclear power related organizations have been actively conducted research on the treatment of nuclear power plant decommissioning waste. In this study, among various types of radioactive waste, stabilization and volume reduction experiments were conducted on radioactive contaminated soil waste. Korea has no experience in decommissioning nuclear power plants, but a large amount of radioactively contaminated soil waste was generated during the decommissioning of the KAERI research reactor (TRIGA Mark- II) and the uranium conversion facility. This case shows the possibility of generating radioactive soil waste from nuclear power plants and nuclear-related facilities sites. Soil waste should be solidified, because its fluidity and dispersibility wastes specified in the notification of the Korea Nuclear Safety and Security Commission. In addition, the solidified waste forms should have sufficient mechanical strength and water resistance. Numerous minerals in the soil are components that can make glass and ceramics, for this reason, glass-ceramic sintered body can be made by appropriate heat and pressure. The sintering conditions of soil were optimized, in order to make better economical and more stable sintered body, some additives (such as additives for glass were mixed) with the soil and sintering experiments were conducted. Uncontaminated natural soil was collected and used for the experiment after air drying. Moisture content, pH, bulk density, and organic content were measured to understand the basic properties of soil, and physicochemical properties of the soil were identified by XRD, XRF, TG, and SEM-EDS analysis. In order to understand the distribution by particle size of the soil, it was divided into Sand (0.05–2 mm) and Fines (< 0.05 mm). The green body was manufactured in the form of a cylinder with a diameter of 13mm and a height of about 10mm. Appropriate pressure (> 150 MPa) was applied to the soil to make a green body, and appropriate heat (> 800°C) was applied to the sintered body to make a sintered body. The sintering was conducted in a muffle furnace in air conditions. The volume reduction and compressive strength of the sintered body for each condition were evaluated.

Kalman Filter-Based Coarse-to-Fine Control for Display Visual Alignment Systems

SangJoo Kwon,Haemin Jeong,Jaewoong Hwang IEEE 2012 IEEE transactions on automation science and engine Vol.9 No.3

<P>A coarse-to-line two-stage control method is investigated for the display visual alignment systems. The proposed visual servo is with hierarchical loops, where the original line but slow vision loop is necessary for the exact localization of alignment marks while the coarse but fast vision loop of exploiting pruned image data is to compensate for the mask-panel misalignment. The degraded resolution of the reduced images is recovered in terms of the Kalman filter which tracks the mark centroids in near realtime. In order to construct the recursive estimation algorithm, the motion model for the moving alignment marks is determined by solving the forward kinematics of positioning mechanism and the measurements from vision sensors are given by means of the geometric template matching (Kwon and Hwang, “Kinematics, pattern recognition, and motion control of mask-panel alignment system,” Control Eng. Practice, vol. 19, pp. 883-892, 2011). Compared with the conventional alignment methods, this approach enables a fast and line alignment control. Experimental results are followed to validate the proposed control framework. Note to Practitioners-In order to successfully apply the developed alignment control to any display manufacturing equipment, it is necessary to well understand the principle of the geometric template matching (GTM) as an alignment mark specific fast algorithm, the details on which can be consulted in our preceding works (Kwon and Hwang, “Kinematics, pattern recognition, and motion control of mask-panel alignment system,” Control Eng. Practice, vol. 19, pp. 883-892, 2011). The new approach has the goal of updating the pose of an alignment mark as fast as the capturing rate of a frame grabber by utilizing pruned image data but recovering the lost resolution in terms of the Kalman filter. For example, in using a common 30 fps grabber, the reduced image of 320 240 pixels is a proper choice to finish the image processing and Kalman filtering within 30 ms under GTM. The proposed algorithm can be implemented in the current industrial display aligners by modifying the control software so that the reference inputs for the distributed joint servos follow the error compensation trajectory in Fig. 4 with the Kalman filter estimates.</P>

커널밀도추정 기반 공정한 분류기 학습 알고리즘

조제웅(Jaewoong Cho),황경조(Gyengjo Hwang),서창호(Changho Suh) 대한전자공학회 2020 대한전자공학회 학술대회 Vol.2020 No.8

기계학습 분야의 빠른 발전과 함께 우리 삶의 많은 부분을 인공지능이 대체하기 시작했다. 특히, 최근에는 간단한 업무뿐만 아니라 채용 서류심사, 범죄자 형량 판단 등 중요한 업무까지 인공지능이 담당하면서, 성별/인종과 같은 민감한 속성에 따라 차별된 결정을 내리지 않는 것이 매우 중요한 사안이 되었다. 우리는 커널밀도추정 기반 공정한 분류기 학습 방법을 개발하였다. 본 논문은 이진분류문제와 두 가지 그룹 공정성 개념(demographic parity, equalized odds)에 초점을 맞추고 있으며 합성데이터 실험을 통해서 제안한 알고리즘이 기존 알고리즘들에 비해 예측 정확도-공정성 트레이드오프 측면에서 성능이 우수함을 입증하였다.

비지도 학습을 활용한 핫 콜드 세그먼트 분류 알고리즘

김재웅(Jaewoong Kim),이다현(Dahyun Lee),황아영(Ahyoung Hwang),이용주(Yongju Lee) 한국정보기술학회 2021 Proceedings of KIIT Conference Vol.2021 No.11

이전 연구에서는 링크드 데이터의 효율적인 검색 및 저장을 위해 핫-콜드 세그먼트 분류 알고리즘을 제안하였다. 하지만 기존의 지도 학습을 활용한 데이터 분류법은 간단하고 높은 정확도를 보였지만 검색 시간이 많이 소요 되는 단점이 존재하였다. 이를 해결하기 위해 본 논문에서는 비지도 학습을 활용한 핫-콜드 세그먼트 분류 알고리즘을 통해 데이터 분류에 소요되는 시간을 줄이고, 향후 새로운 특성이 추가되었을 경우에도 성능을 유지할 수 있도록 비지도 학습 분류를 수행한다. In the previous work, a hot-cold segment classification algorithm was proposed for efficient retrieval and storage of Linked Data. Although the existing classification method using supervised learning was simple and showed high accuracy, it had the disadvantage of taking a lot of retrieval time. To solve this problem, in this paper, the time required for data classification is reduced through the hot-cold segment classification algorithm using unsupervised learning, and unsupervised learning classification is performed to maintain performance even when new features are added in the future.

Alloy617과 12Cr강의 이종 용접과 기계적 특성 평가

윤재웅(Jaewoong Yoon),황정호(Jungho Hwang),이주화(Juhwa Lee),김태민(Taemin Kim),배동호(Dongho Bae) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

Currently, dependence on thermal power generation is quite high in the world wide. Accordingly, it caused the problem such as carbon dioxide and greenhouse gas emission. In order to reduce the problems, various studies have been conducted and increasing the efficiency of thermal power generation is one of them. It must be raised to main steam temperature to increase the power generation efficiency. In developed countries, it have studied the A-USC thermal power plant using the main steam temperature above 700℃. It is necessary to develop materials that satisfy the durability and reliability in extreme environments. Prior to application to the actual power plant system, fundamental research is needed such as welding procedure, mechanical properties. In this paper, dissimilar welding using major materials candidate, Alloy617 and 12Cr steel were performed, and weld metal was metallurgically analyzed and mechanically assessed.

청소년의 연예인에 대한 관심과 섭식장애

심재웅(Jaewoong Shim),황재원(Jaewon Hwang) 한국언론학회 2016 한국언론학보 Vol.60 No.4

STS316 배관에서 Acoustic Emission 법을 이용한 응력부식균열 탐지에 관한 연구

박재웅(Jaewoong Bak),배승기(Seunggi Bae),황웅기(Woonggi Hwang),이보영(Boyoung Lee),이상율(SangYul Lee) 대한용접·접합학회 2015 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2015 No.05

Evaluation of Sintering Characteristics for Radioactive Precipitates Generated During Waste Treatment Processes

Keunyoung Lee,Jaewoong Hwang,Sungjune Sohn,Min Ku Jeon 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

Various types of radioactive liquid and solid wastes are generated during the operation and decommissioning of nuclear power plants. To remove radionuclides Co-60, Cs-137 etc. from a liquid waste, the ion-exchange process based on organic resins has been commonly used for the operation of nuclear facilities. Due to the considerations for the final disposal of process endproduct, other treatment methods such as adsorption, precipitation using some inorganic materials have been suggested to prepare for large amounts of waste during decommissioning. This study evaluated sintering characteristics for radioactive precipitates generated during the liquid waste treatment process. The volume reduction efficiency and compressive strength of sintered pellets were the major parameters for the evaluation. Major components of a simulated precipitate were some coagulated (oxy) hydroxides containing light elements, such as Si, Al, Mg, Ca, and zeolite particles. Green pellets compressed to around 100 MPa were heated at a range of 750~850°C to synthesize sintered pellets. It was observed that the volume reduction percentages were higher than 50% in the appropriate sintering conditions. The volume reduction was caused by the reduction of void space between particles, which is an evidence of partial glassification and ceramization of the precipitates. This result can also be attributed to conversion reactions of zeolite particles into other minerals. The compressive strength ranged from 6 to 19 MPa. These results also showed a significant correlation with the volume reduction of sintered body. Although our lab-scale experiments showed many benefits of sintering for the precipitates, optimized conditions are needed for large-scale practical applications. Evaluation of sintering characteristics as a function of pellet size and further testing will be conducted in the future.