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RISS 인기검색어
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- 저자 : Seokyoung Oh (검색결과 6 건)
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Seokyoung Oh,Byoungkwan Kim,Jaehyuk Kang,Hyun-min Ma,Younglim Shin,Wooyong Um 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
The homogeneity of radioactive spent ion exchange resins (IERs) distribution inside waste form is one of the important characteristics for acceptance of waste forms in long-term storage because heterogenous immobilization can lead to the poor structural stability of waste form. In this study, the homogeneity of metakaolin-based geopolymer waste form containing simulant IERs was evaluated using a laser-induced breakdown spectroscopy (LIBS) and statistical approach. The cation-anion mixed IERs (IRN150) were used to prepare the simulant spent IERs contaminated by non-radioactive Cs, Fe, Cr, Mn, Ni, Co, and Sr (0.44, 8.03, 6.22, 4.21, 4.66, 0.48, and 0.90 mg/g-dried IER, respectively). The K2SiO3 solution to metakaolin ratio was kept constant at 1.2 and spent IERs loading was 5wt%. For the synthesis of homogeneous geopolymer waste form, spent IERs were mixed with K2SiO3 solution and metakaolin first, and then the fresh mixture slurry was poured into plastic molds (diameter: 2.9 cm and height: 6.0 cm). The heterogeneous geopolymer waste form was also fabricated by stacking two kinds of mixtures (8wt% IERs loading in bottom and 2wt% in top) in one mold. Geopolymers were cured for 7d (1d at room temperature and 6d at 60°C). The hardened geopolymers were cut into top, middle, and bottom parts. The LIBS spectra and intensities for Cs were obtained from the top and bottom of each part. Cs was selected for target nuclide because of its good sensitivity for measurement. Shapiro-Wilk test was performed to determine the normality of LIBS data, and it revealed that data from the homogeneous sample is normal distribution (p-value = 0.9246, if p-value is higher than 0.05, it is considered as normal distribution). However, data from the heterogeneous sample showed abnormal distribution (p-value = 7.765×10-8). The coefficient of variation (CoV) was also calculated to examine the dispersion of data. It was 31.3% and 51.8% from homogeneous and heterogeneous samples, respectively. These results suggest that LIBS analysis and statistical approaches can be used to evaluate the homogeneity of waste forms for the acceptance criterion in repositories.
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오석영(Seokyoung Oh) 한국배움학회 2010 배움학 연구 Vol.2 No.2
The purpose of this study is to identify the common characteristics between organizational learning process and human being learning in their innate ability to learn. The common characteristics are as follows: First, the learning begins with insufficiency to improvement and a will for change. Second, the learning how to learn, so called deutero-learning is embedded in both sides. Third, problem-based learning, focusing experience, is important to actualize what they learn. And finally, the concept of unlearning is emphasized to drive them to new one. This research conclude that these four are regarded as core competencies to make organizations open community and there are human being learning ability as a driver. 본 연구는 기업이 가지고 있는 배움공동체적 특징을 조직학습적 시각에서 살펴보고 인간의 배움과 기업 내 조직학습활동의 유사성을 문헌조사를 통해 고찰해 보았으며 다음 네 가지로 정리하였다. 첫째, 기업 내 내적 결핍과 변화의지에서 공동체 학습이 시작되며, 둘째, 기업은 재학습(deutero-learning)을 통해 올바른 학습 방향을 설정하고, 셋째, 문제해결 중심의 학습을 통해 실천력이 향상되며, 넷째, 비움의 학습(unlearning)을 통해 새로운 지식을 창조할 수 있는 유연성을 갖춘다. 이러한 조직학습의 특징들은 인간의 배움에 대한 욕구, 배움본능, 실천지, 비움 등과 같은 배움의 속성과 맥을 같이하여 기업이 변화하는 환경 속에서 능동적이고 창조적으로 행동하는 근간이며 기업의 경쟁력인 것이다. 따라서 기업은 변화하는 조직학습을 통해 조직의 갱신(organizational renewal)을 추구하는 열린 공동체이며 이를 실천하는데 조직의 배움력이 있다.
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Solidification of Radioactively Contaminated Soils Using Cement Waste Forms
Hyun-min Ma,Byoungkwan Kim,Jaehyuk Kang,Seokyoung Oh,Younglim Shin,Wooyong Um 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
The soils contaminated with radionuclides such as Cs-137 and Sr-90 should be solidified using a binder matrix, because radioactively contaminated soils pose environmental concerns and human health problems. Ordinary Portland cement has been widely used to solidify various radioactive wastes due to its low cost and simple process. In this study, simulant soil waste was solidified using cement waste form. The soils were collected around ‘Kori Nuclear Power Plant Unit 1’ and they were contaminated with the prepared simulant liquid waste containing Fe, Cr, Cs, Ni, Co, and Mn. The water-to-dry ingredients (W/D) ratio of cement waste form was 0.40. The cement paste was poured into a cubic mold (5×5×5 cm) and then cured for 28 days at room temperature. The 28-day compressive strength, water immersion, and EPA1311-toxicity characteristic leaching procedure (TCLP) tests were performed to evaluate the structural stability of cement waste form. The compressive strength was not proportional to soil waste loading, and the lowest compressive strength (4±0.1 MPa) was achieved in cement waste form containing 50wt% soil waste. After the water immersion test for 90 days, the compressive strength of cement waste form with 50wt% soil waste increased to 7.5±0.6 MPa, meeting the waste form acceptance criteria in the repository. It is believed that long-term water immersion test contributed to the additional curing and hydration reaction, resulting in the enhanced compressive strength. As a result of the TCLP test, the released amount of As, Ba, Cd, Cr, Pb, Se, Co, Cs, and Sr was less than the domestic and international standards. These results imply that cement waste form can be a promising candidate for the solidification of radioactive soil wastes.
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Juwon Kim,Sunghyun Nam,Gunhee Oh,Seokyoung Kim,Sanghyeon Lee,Heoncheol Lee 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
This paper addresses the problem of the recognition and localization of multiple targets while building a three-dimensional map using 3D SLAM (Simultaneous Localization and Mapping) in indoor environments. Since stationary target search systems have the limitations that the target search is conducted passively, this paper presents an implementation of a multi-target search system with a mobile robot and multiple sensors. The mobile multi-target search system consists of a 3D LiDAR and a depth camera on top of a two-wheel mobile robot. Multiple targets are recognized by YOLO (You Only Look Once), and the relative position between the mobile robot and the recognized target is measured by the depth information obtained by the depth camera. The 3D SLAM is implemented with LeGO-LOAM (Lightweight and Ground Optimized Lidar Odometry and Mapping), and the positions of the recognized multiple targets are described with the 3D map. The mobile multi-target search system was implemented on ROS (Robot Operating System) and tested in multiple indoor environments.
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