Solubility of Radionuclides Under Near and Far Field Conditions: Effect of Organic Complexing Agents

Bolam Kim,Ahsan Abdul Ghani,Youngsu Lim,Dae Sung Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Organic complexing agents which are contained in the radioactive waste can form the complex with radionuclides and enhance the solubility of radionuclides. The mobility of radionuclides to the far-field from the repository will be increased by radionuclide-ligand complex formation. Therefore, the assessment of the radionuclides’ solubility should be performed in the presence of organic complexing agents. In this study, five radionuclides (cobalt, strontium, iodine, cesium, and uranium) and three organic complexing agents (ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and isosaccharinic acid (ISA)) were selected as model radionuclides and organic complexing agents, respectively. For simulating the in-situ condition, the groundwater near the repository was collected and applied in solubility experiments and the solubility was measured in various environmental conditions such as different pHs (7, 9, 11, and 13), temperatures (10°C, 20°C, and 40°C), and a range of organic complexing agent concentrations (10-5, 10-4, 10-3, and 10-2 M). In cases of cesium and iodine, they were very soluble in all conditions, and the effect on their solubilities was not observed. However, at high pHs, cobalt and strontium showed lower solubilities than at neutral pH and the solubility enhancement by the organic complexing agents was significant. Moreover, the effects of each organic ligand showed obvious differences and were in the order of EDTA > NTA > ISA. The solubility of uranium was increased with increasing the organic ligand concentration at lower pHs, but the organic complexing agents did not cause a remarkable difference at high pHs. According to these results, the presence of complexing agents could enhance the radionuclides’ solubility and increase the potential to release the radionuclides to the far-field from the repository. Solubility experiments of other major radionuclides in the repository are in progress.

Experimental Analysis and Mathematical Prediction of Radionuclides’ Solubility Using Support Vector Machine Model: Effect of Organic Complexing Agents on Radionuclides’ Solubility

Bolam Kim,Gi-Taek Oh,Youngsu Lim,Jinseob Kim,Juhui Park,Seongju Lee,Jiseon Jang,Seho Choi,Myunggoo Kang,Jaechul Ha,Chun-Hyung Cho,Min-Woo Lee,Dae Sung Lee 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

The organic complexing agents such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and isosaccharinic acid (ISA) can enhance the radionuclides’ solubility and have the potential to induce the acceleration of radionuclides’ mobility to a far-field from the radioactive waste repository. Hence, it is essential to evaluate the effect of organic complexing agents on radionuclide solubility through experimental analysis under similar conditions to those at the radioactive waste disposal site. In this study, five radionuclides (cesium, cobalt, strontium, iodine, and uranium) and three organic complexing agents (EDTA, NTA, and ISA) were selected as model substances. To simulate environmental conditions, the groundwater was collected near the repository and applied for solubility experiments. The solubility experiments were carried out under various ranges of pHs (7, 9, 11, and 13), temperatures (10°C, 20°C, and 40°C), and concentrations of organic complexing agents (0, 10-5, 10-4, 10-3, and 10-2 M). Experimental results showed that the presence of organic complexing agents significantly increased the solubility of the radionuclides. Cobalt and strontium had high solubility enhancement factors, even at low concentrations of organic complexing agents. We also developed a support vector machine (SVM) model using some of the experimental data and validated it using the rest of the solubility data. The root mean square error (RMSE) in the training and validation sets was 0.012 and 0.016, respectively. The SVM model allowed us to estimate the solubility value under untested conditions (e.g., pH 12, temperature 30°C, ISA 5×10-4 M). Therefore, our experimental solubility data and the SVM model can be used to predict radionuclide solubility and solubility enhancement by organic complexing agents under various conditions.

논문 : 무전해 Ni-W-P 도금에서 착화제의 종류가 피막특성에 미치는 영향

조진기 ( Jin Ki Cho ),박상욱 ( Sang Wook Park ),강성군 ( Seung Goon Kang ),손성호 ( Seong Ho Son ) 대한금속재료학회 ( 구 대한금속학회 ) 2008 대한금속·재료학회지 Vol.46 No.11

Deposition characteristics of electroless plated Ni-W-P films were investigated for various complexing agents. Used complexing agents are sodium citrate, sodium gluconate and sodium malonate. In this study, the existing mixed potential theory could explain the overall mechanism of Ni-W-P electroless plating for all complexing agents. The deposition rate could be also expected by the theory. The deposited Ni- W-P films were evaluated in term of surface hardness and corrosion resistance. Microhardness of the deposit increased about 1,000 Hv after heat treatment for one hour at 400℃, because it was above the crystallization temperature of Ni3P. The deposited Ni-W-P films can exhibit excellent corrosion resistance in using sodium malonate as a complexing agent, the other hand the using sodium gluconate was the worst corrosion resistance. The worst corrosion resistance was due to a large number of nano-sized pin-holes or small pores. The plating current at the mixed potential increases when the using sodium malonate as a complexing agent, it was explained by the cross section.

Active Insolubilized Antibiotics Based on Cotton Xanthate-Zirconium Complex

Kim, Young-Mi,Lee, Kyung Jin,Jung, Yun Jin 부산대학교 신약개발연구소 1988 藥學硏究誌 Vol.22 No.1

약전품 gause를 알카리성에서 이황화 탄소와 반응시켜 xanthate group을 도입시킨후 zirconium용액과 반응시켜 cotton xanthate-zirconium complex를 만들었다. 상기 제품을 증류수로 충분히 세척하고 건조시킨후 tetracycline, streptomycin, neomycin, 또는 pyrithione염의 수용액과 충분히 반응시켰다. 약물과 처리한 제품은 인산 완충액(pH5.1), 식염수(0.5M) 및 증류수로 차례로 충분히 세척하고 aureus, Streptococcus faecalis, Gram 음성균인 Escherichia coli, Enterobacter aerogenes와 진균으로서는 Aspergillus niger를 사용하였다. Cotton xanthate-zirconium-antimicrobial agent complex는 모두 항미생물 작용을 나타내었다. 그러나 cotton xanthate-zirconium은 그 자체로서는 활성을 나타내지 않았다. 또한 cotton을 동일한 조작으로 zirconium 및 약물과 차례로 처리하고 세척 건조한 제품도 활성을 나타내지 않았다. 따라서 단순히 물리적으로 결합된 약물은 세척과정에서 제거되는 것으로 보이며 약물의 결합은 cotton표면에 도입된 xanthate group과 zirconium ion의 cotton xanthate-zirconium-antimicrobial agent complex를 형성하여 이루어 지는 것으로 생각된다. Cotton xanthate, which was prepared by reacting cotton with carbon disulfide in alkaline solution, was treated with a zirconium containing solution to form cotton xanthate-zirconium complex. The metal-bound cotton xanthate was treated with a solution of a salt of tetracycline, streptomycin, neomycin, or pyrithione to produce cotton xanthate-zirconium-antimicrobial agent complex. Antimicrobial activity of the products was tested against gram-positive Staphylococcus aureus, Streptococcus faecalis, and gram-negative Escherichia coli, Enterobacter aerogenes and the fungus Aspergillus niger, employing a modified ditch plate method. Coupling of antimicrobial agents is believed to take place by chelation with the zirconium ion which is already bound to the xanthate group on the surface of the cotton fabric to form cotton xanthate-antimicrobial agent complex. That the antimicrobial agents had complex with the cotton-xanthate-zirconium complex is that cotton xanthate-zirconium-antimicrobial agents exhibited antimicrobial activities whereas the cotton xanthate-zirconium complex itself was inactive.

티오말산을 착화제로 하고 아미노에탄티올을 환원제로 하는 비시안계 무전해 Au 도금액의 석출 거동 및 도금 특성

한재호,김동현 한국표면공학회 2022 한국표면공학회지 Vol.55 No.2

Gold plating is used as a coating of connecter in printed circuit boards, ceramic integrated circuit packages, semiconductor devices and so on, because the film has excellent electric conductivity, solderability and chemical properties such as durability to acid and other chemicals. As increasing the demand for miniaturization of printed circuit boards and downsizing of electronic devices, several types of electroless gold plating solutions have been developed. Most of these conventional gold plating solutions contain cyanide compounds as a complexing agent. The gold film obtained from such baths usually satisfies the requirements for electronic parts mentioned above. However, cyanide bath is highly toxic and it always has some possibility to cause serious problems in working environment or other administrative aspects. The object of this investigation was to develop a cyanide-free electroless gold plating process that assures the high stability of the solution and gives the excellent solderability of the deposited film. The investigation reported herein is intended to establish plating bath composition and plating conditions for electroless gold plating, with thiomalic acid as a complexing agent. At the same time, we have investigated the solution stability against nickel ion and pull strength of solder ball. Furthermore, by examining the characteristics of the plated Au plating film, the problems of the newly developed electroless Au plating solution were improved and the applicability to various industrial fields was examined. New type electroless gold-plating bath which containing thiomalic acid as a complexing agent showing so good solution stability and film properties as cyanide bath. And this bath shows the excellent stability even if the dissolved nickel ion was added from under coated nickel film, which can be used at the neutral pH range.

A Study on the Corrosion Effects by Addition Complexing Agent in the Copper CMP Process

Sang-YongKim,Nam-HoonKim,In-PyoKim,Eui-GooChang,Yong-JinSeo,Hun-SangChung 한국전기전자재료학회 2003 Transactions on Electrical and Electronic Material Vol.4 No.6

Copper CMP in terms of the effect of slurry chemicals (oxidizer, corrosion inhibitor, complexing agent) on the process characteristics has been performed. Corrosion inhibitors, benzotriazole (BTA) and tolytriazol (TTA) were used to control the removal rate and avoid isotropic etching. When complexing agent is added with H2O2 2 wt% in the slurry, the corrosion rate was presented very well. In the case of complexing agent, it was estimated that the proper concentration is 1 wt%, because the addition of tartaric acid to alumina slurry causes low pH and the slurry dispersion stability become unstable. There was not much change of the removal rate. It was assumed that BTA 0.05 wt% is suitable. Most of all, it was appeared that BTA is possible to be replaced by TTA. TTA was distinguished for the effect among complexing agents.

교통시스템분석시 에이젠트기반모형기법의 적용

이종호 대한교통학회 2003 대한교통학회지 Vol.21 No.1

교통문제는 사회시스템이 복잡해짐에 따라 더욱 대처하기 어려운 국면으로 가고 있다. 따라서 교통시스템의 변화 예측도 용이하지 않다. 복잡계(complex system)의 하나로 볼 수 있는 교통시스템을 대처하는데 있어, 전통적인 상의하달(上意下達) 접근에 한계가 있음을 부인할 수 없다. 지난 10여년 동안 물리학, 시스템공학, 컴퓨터공학 분야 등 다양한 분야에서 복잡계에 대한 활발한 연구가 진행되고 있다. 복잡계의 해석을 위한 새로운 개념과 접근기법들이 도입되고 있는데, 그들 중 에이젠트기반모형(agent-based modelling)은 교통분야에 적용 가능한 매우 흥미를 있는 기법으로 보인다. 본 글에서는 에이젠트기반모형이 무엇이며, 어떻게 사용되고 있으며, 교통분야에서의 적용가능성을 검토하였다. 본 글에서 제시한 에이젠트기반접근은 기존 방법과는 다른 하의상달(下意上違) 방식의 기법이다. 이는 시스템의 개별 구성원인 에이젠트의 행태와 에이젠트간의 상호작용에 초점을 둔다. 에이젠트의 행태와 상호작용의 규칙이 변함에 따라 전 에이젠트시스템에 나타나는 변화를 추적할 수 있다. 오늘날 교통문제의 복잡성은 교통시스템의 더욱 세분화된 하부시스템의 다양화와 상호작용, 그리고 개별 차량 또는 운전자의 행태와 상호작용에서 기인된다고 볼 수 있다. 따라서 에이젠트기반의 접근은 아직 연구는 미흡하지만 복잡한 교통시스템의 운영과 분석에 적용잠재력이 큰 기법으로 판단된다.

A Two-Agent Single-Machine Scheduling Problem with Periodic and Common Due Dates

Byung-Cheon Choi(최병천),Yunhong Min(민윤홍) 대한산업공학회 2020 대한산업공학회지 Vol.46 No.5

We consider a single-machine scheduling problem with two agents. The objective is to minimize the objective function of agent 1 while that of agent 2 is below a given threshold. The objective function of agent 1 is the total weighted completion time, while that of agent 2 is the total weighted number of tardy jobs. Furthermore, the due date of agent 2 is assigned not to the specific job but to the position. Firstly, we show that the problem with the identical intervals between the consecutive due dates remains strongly NP-hard, even if the weights of jobs of agent 2 are identical. Finally, we proved the weak NP-hardness of the problem with a common due date.

금융위기 이후 경제학의 새로운 분석도구로서의 복잡계 이론

이대엽,박하일 梨花女子大學校 社會科學大學 社會科學硏究所 2012 사회과학연구논총 Vol.28 No.-

복잡계 이론은 시스템 동학의 갑작스런 변화를 설명하고 이를 사전에 예측하기 위해 발전해 왔으며 이와 관련된 복잡계 이론의 연구들은 최근의 금융위기를 이해하는 데 새로운 시각을 제시한다. 복잡계 이론은 복잡계를 구성하는 개별 구성요소들보다는 개별 구성요소들 간의 복잡한 상호작용이 야기하는 출현적 현상에 주목한다는 점에서 금융 시스템에서의 출현적 현상인 시스템 리스크를 이해하는데 기여하고 있다. 복잡계 이론은 향후 다음과 같은 분야에서 활용도가 높아질 것으로 예상된다. 복잡 네트워크 이론은 시스템 리스크의 측정 등 거시건전성의 부문 간 차원을 이해하는 데 유용하며, 복잡계의 임계 전환(critical transition)은 거시건전성의 동태적 차원을 분석하는 데 활용될 수 있다. 또한 행위자 기반 모형(ABM)은 현실의 복잡한 측면들을 모형에 도입하고 경제주체의 제한된 합리성과 학습 등을 중시한다는 점에서 경제주체의 높은 합리성을 가정하고 있는 동태적․확률적 일반균형(DSGE) 모형과 상호 보완적 역할을 수행할 것으로 기대된다. Complex systems theory has been developed to explain sudden changes in system dynamics and to make ex-ante predictions on such changes. Relevant studies on this theory provide new perspectives for understanding the recent financial crisis. Complex systems theory help understand systemic risk which is an emergent phenomenon in a financial system, in that it focuses on the emergent property resulting from complex interactions among individual components rather than on each component comprising the complexity. The use of complex systems theory is expected to increase in areas as follows. First, complex networks theory is useful in understanding the cross-sectional aspect of macro-prudentiality like the evaluation of systemic risk. Second, the studies on the critical transition of complex systems can shed some light on the dynamic aspect of macro-prudentiality. Also, an Agent-Based Model (ABM) is expected to play complementary roles to a Dynamic Stochastic General Equilibrium (DSGE) model which assumes high rationality of economic agents, in that agent-based modeling includes complex aspects of the real world into the model and places importance on the bounded rationality and learning of economic agents.

A Study on the Determination of Organic Chelating Agents in a Variety of Radioactive Wastes

Hyejin Cho,Hye-Ryun Cho,Jail Park 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

Low- and intermediate-level radioactive waste for permanent disposal often contains organic complexing agents, so-called chelating agents. Organic complexing agents, which are polycarboxylic acids, can increase the mobility of radionuclides into the environment by forming water-soluble complexes with most heavy metals. Therefore, analyzing the complexing agents in radioactive waste is crucial for comprehensive management of nuclear wastes. According to regulatory guidelines, specifically Notice No. 2021-16 issued by the Nuclear Safety and Security Commission, the determination of chelating agent content in radioactive waste materials is required to ensure proper management and safe disposal. However, only a few methods are available to analyze the chelators in various matrices such as concrete, metals, soil, and mixed solid wastes like plastics, vinyl, and rubber. Recently, we found a UV-Vis method based on an enzymatic reaction is inadequate for analyzing citric acid in radioactive waste with a complex matrix like concrete. To address this, we developed a method to determine the contents of EDTA and NTA using a UV-Vis spectrophotometer and citric acid using ion chromatography. The results showed good validity and reliability to determine the chelating agents in various radioactive wastes.