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A Study on the Sintering Stabilization Method of Cs-contaminated Spent Adsorbent
Keunyoung Lee,Maengkyo Oh,Jaewoong Hwang,Min Ku Jeon 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
This study evaluated the synthesis of optimal materials for high efficiency adsorption and removal characteristics of Cs-137 for radioactive contaminated water, and considered thermal treatment methods to stabilize the spent adsorbent generated after treatment. We synthesized a composite adsorbent with a combination of impregnating metal ferrocyanide that improves the selectivity of Cs adsorption with zeolite capable of removing Cs as a support. The Cs removal efficiency of the composite adsorbent was evaluated, and the stability change of Cs according to the high-temperature sintering was evaluated as a stabilization method of the spent adsorbent. The metal ferrocyanide content of the adsorbent was in the range of 11.8~36.0%. The adsorption experiments were performed using a simulated liquid waste to have a total Cs concentration of 1 mg/L while containing a trace amount of Cs-137, and then gamma radioactivity was analyzed. In order to evaluate the stabilization of the spent adsorbent, heat treatment was performed in the range of 500~1,100°C, and the volatilization rate of Cs during heat treatment and the leaching rate of Cs after heat treatment were compared. In the adsorption experiment, the Cs removal efficiency was higher than 99%, regardless of the amount of metal ferrocyanide in the composite adsorbent. In the sintering experiment on the spent adsorbent, it was confirmed that there was no volatilization of Cs up to 850°C, and then the volatilization rate increased as the heating temperature increased. On the other hand, the leaching rate of Cs in the sintered adsorbent tends to significantly decrease as the heating temperature increases, so that Cs can be stabilized in the sintered body. In addition, as the content of metal ferrocyanide increases, the volatilization rate of Cs rapidly increases, indicating that the unstable metal ferrocyanide in the adsorbent may adversely affect the removal of Cs as well as the thermal treatment stability.
Keunyoung Lee,Maengkyo Oh,Richard I. Foster,Kwang-Wook Kim,Sungjune Sohn,Min Ku Jeon,Bum-Kyoung Seo 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
Radioactive waste generated in large quantities from NPP decommissioning has various physicochemical and radiological characteristics, and therefore treatment technologies suitable for those characteristics should be developed. Radioactively contaminated concrete waste is one of major decommissioning wastes. The disposal cost of radioactive concrete waste is considerable portion for the total budget of NPP decommissioning. In this study, we developed an integrated technology with thermomechanical and chemical methods for volume reduction of concrete waste and stabilization of secondary waste. The unit devices for the treatment process were also studied at bench-scale tests. The volume of radioactive concrete waste was effectively reduced by separating clean aggregate from the concrete. The separated aggregate satisfied the clearance criteria in the test using radionuclides. The treatment of secondary waste from the chemical separation step was optimally designed, and the stabilization method was found for the waste form to meet the final disposal criteria in the repository site. The final volume reduction rates of 56.4~75.4% were possible according to the application scenario of our processes under simulated conditions. The commercial-scale system designs for the thermomechanical and chemical processes were completed. Also, it was found that the disposal cost for the contaminated concrete waste at domestic NPP could be reduced by more than 20 billion won per each unit. Therefore, it is expected that the application of this technology will improve the utilization of the radioactive waste disposal space and significantly reduce the waste disposal cost.
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.
Stainless steel promoted the electrochemical oxidation of amines into imines
Lee Keunyoung,Choi Hyebin,An Jaun,Kwon Ki‐Young 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.7
We report the electrochemical oxidation of benzylamine (BA) into the imine by applying a bare stainless steel mesh (SSM) as an anode. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) elemental mapping analysis confirmed that there was no corrosion on the surface of SSM after an anodic electrolysis. Based on the gas chromatography (GC) analysis and electrochemical results, it was confirmed that conversion of BA with SSM was approximately 3.3 times higher than with Pt electrode. This work suggests that the anodic electrolysis with a bare SSM could be a promising route to electrochemical oxidation of BA in the absence of oxidizing agents.
Jieun Lee,Sung Joon Cho,Kang Soo Lee,Keunyoung Yook,최아영,Sungjae Lee,김보라,Keung-Hyang Kim,Tae Kyou Choi,이상혁 대한정신약물학회 2011 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.9 No.2
Objective: Some patients with schizophrenia may need mirtazapine augmentation to improve negative and cognitive symptoms. However there have been a few studies about the tolerability of mirtazapine augmentation to antipsychotics such as akathisia,extrapyramydal symptoms, weight gain, and body mass index (BMI). Methods: This study was an eight-week double-blind, randomized controlled trial (RCT) of mirtazapine augmentation to risperidone. Twenty-one stabilized participants diagnosed with schizophrenia and undergoing treatment with risperidone were randomized to adjunctive treatment with mirtazapine (15 mg/day for the first two weeks, 30 mg/day for the next six weeks) or placebo. Eleven patients were assigned to the mirtazapine group, and nine patients were given placebo. Results: There was no significant difference between the mirtazapine and placebo groups with respect to Barnes Akathisia rating Scale (BAS) and Sympsom-Angus Scale (SAS). However, the mirtazapine group exhibited a statistically significant increase in weight and BMI (p<0.05). Conclusion: These results suggest that mirtazapine augmentation can be tolerable in schizophrenic patients treated with risperidone;however, we should pay attention to the weight gain with mirtazapine. Our results should be replicated in a large-scale lengthy trial.
이근영(Lee KeunYoung),장유경(Chang-Song YouKung),임현정(Lim HyunJung) 한국열린유아교육학회 2004 열린유아교육연구 Vol.9 No.1
본 연구에서는 자녀양육 초기 영아모의 자녀양육지식 수준을 살펴보기 위해 4개월 영아를 자녀로 둔 중산층 영아모 440명을 대상으로 자녀양육지식의 정도와 특성을 살펴보았다. 연구 결과, 영아모의 자녀양육지식에 대한 평균 정답률은 50 6%로서, 어린영아 자녀를 둔 어머니들이 전반적으로 자녀양육지식 정도가 높지 않으며 특히 영아들의 초기 발달에 대해 잘 알지 못하는 것으로 나타났다. 또한 영아모의 학력이 높을수록, 연령이 많을수록, 그리고 자녀수가 많을수록 자녀양육지식을 많이 아는 것으로 나타났다. 본 연구 결과는 향휴 부모교육 프로그램이 프로그램의 슈혜 대상인 부모의 특성 뿐 아니라 부모의 유아 발달에 대한 지식과 정보 수준, 자녀양육지식의 하위 영역 중 부족한 부분을 고려하여 수준별 단계적 프로그램으로 계발되어야 할 것을 시사한다. The purpose of this study IS co examine korean mothers' knowledge of child development and child-rearing. Subjects of the study were 440 middle-class mothers of 4-month-old infants. The findings of this study are as follows: First, mothers' knowledge level of child development and child-rearing was generally low. Second, mothers' knowledge of child development and child-rearing has positive correlations with mothers' educational background, mothers' age, and the number of children. These results suggest that mothers' knowledge level of child development and child-rearing should be considered for developing parent education programs.
Bone graft materials for current implant dentistry
Jang Keunyoung,Lee Jong-Ho,Oh Sung-Hwan,Ham Byung-Do,Chung Sung-Min,Lee Jeong Keun,Ku Jeong-Kui 대한치과이식(임프란트)학회 2020 The Korean Academy of Implant Dentistry Vol.39 No.1
In 2018, the Autumn conference of the Korean Academy of Implant Dentistry presented a lecture on the latest knowledge on bone grafts for implant dentistry. The author summarized the characteristics, advantages, and limitations of four typical bone graft materials, which are autogenous bone graft, autogenous tooth derived bone graft, xenograft, and alloplastic graft material. In addition, this study suggested the theoretical background through a literature review on bone graft surgery in current implant dentistry.