• Korean Journal of Mineralogy and Petrology
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• v.36 no.1
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• pp.33-40
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• 2023

Todorokite is a manganese oxide mineral containing Mg²⁺ in a tunnel structure in which MnO₆ octahedra share corners. In order to investigate the suitability and efficiency of high temperature-treated todorokite as a material for adsorption and fixation of Cs, Cs was ion exchanged and the amount of leached Cs from todorokite was measured. The todorokite used in this study was synthesized by transforming Na-birnessite to Mg-buserite and used as a precursor. After high temperature treatment, Cs exchanged todorokite changed to birnessite and hausmannite as the temperature increased. The amount of leached Cs was investigated for Cs exchanged todorokite which was reacted with distilled water and 1 M NaCl solution at different reaction times. In general, for the samples reacted with 1 M NaCl solution, the fixation of Cs was quite effective, although the amount of leached Cs was greater due to the ion exchange reaction with Na. As the treatment temperature increased, the amount of leached Cs increased and then decreased again, which was related to the mineral phases formed at each temperature. As birnessite was formed, the amount of leached Cs increased, but as birnessite decreased, that decreased again. As the mineral phase changed to hausemanite, the amount of Cs decreased rapidly. The results of our study show that Cs exchanged todorokite can be used as a material that effectively fixes Cs and prevents its diffusion by high temperature treatment.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1930-1932
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• 2005

Colloidal Silica(CS)/methyltrimethoxy silane(MTMS) and CS/MTMS/epoxy silane(Es) sol solutions were prepared in variation with synthesizing parameters such as kinds of CS, kinds of silane and reaction time. In order to understand its physical and chemical properties, sol-gel coating films on glass were fabricated. In the case of CS/MTMS sol, the coating films had high contact angle and more enhanced flat surface than those in the case of CS/MTMS/ES sol. Also, the coating films obtained from single CS had a better flat surface than those obtained from mixed CS. In the case of thermal stability, thermal dissociation of CS/MTMS and CS/MTMS/ES sol-gel coating films did not occur up to $550^{\circ}C$ and $440^{\circ}C$ respectively. The thickness of coating films obtained from CS/MTMS sol increased than those of CS/MTMS/ES sol. In addition, the coating films obtained from single CS were more thicker than those obtained from mixed CS.

• Clean Technology
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• v.19 no.1
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• pp.13-21
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• 2013

The hydrogenolysis of cellulose into polyols was examined over Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ catalysts containing different Cs fractions. The surface area and Pt dispersion of Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ catalysts were found to increase with Cs content. Similar polyol yields were obtained over Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ catalysts irrespective of their Cs content. The catalytic activity of Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ was comparable to that of Ni/W/SBA-15 and combined catalytic systems such as Pt/AC+$H_3PW_{12}O_{40}$ and Pt/AC + $Cs_{3.0}PW_{12}O_{40}$. Some polyanion species were found to leach from the Pt/$Cs_xH_{3-x}PW_{12}O_{40}$ catalyst during the course of the reaction.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.545-550
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• 1998

PWR 사용후핵연료 내에 존재하는 $^{134}$ Cs/$^{137}$Cs 및 $^{154}$ Eu/$^{137}$Cs의 감마선 핵종비를 써서 각각 연소도를 결정하고, 그들의 차이가 최소가 되는 시간을 찾는 방법으로 사용후핵연료의 냉각시간을 결정하였다. $^{134}$ Cs/$^{137}$ Cs 및 $^{154}$ Eu/$^{137}$Cs의 핵종비로부터 연소도를 구하는 방법은 이들 핵종비에 대한 ORIGEN-5 코드 계산과 감마스캐닝 실험 결과를 비교하는 것이었다$^{[1]}$ . 사용후핵연료의 냉각시간을 임의의 시간으로 가정하고 핵종비 $^{134}$ Cs/$^{137}$ Cs을 써서 구한 연소도와 $^{154}$ Eu/$^{137}$Cs를 써서 구한 연소도의 차이를 계산했으며, 이 차이는 실제 측정대상 핵연료의 냉각시간에서 최소가 될 것을 기대하였다. 감마선 방출 핵분열생성물인 $^{134}$ Cs와 $^{154}$ Eu는 비교적 긴 반감기를 갖고 있으면서도 또 이들의 반감기 차이가 약 6.4년이나 되므로 기존의 방법$^{[2]}$ 에 비해 넓은 범위의 냉각시간을 정확하게 측정할 수 있었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.509-514
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• 1998

ORIGEN-S 전산코드로 계산된 가압경수로(PWR)사용후핵연료 내에 존재하는 방사성핵종비 $^{134}$ Cs/$^{137}$Cs 및 $^{154}$ Eu/$^{137}$Cs 를 감마선 분광실험으로 측정한 값과 비교하여 핵연료의 연소도를 결정하였다. 고리 1호기 및 2호기 사용후핵연료봉에 대한 감마선 분광실험을 한국원자력연구소 조사재시험시설(IMEF)과 조사후시험시설(PIEF)의 시험기기 및 장치를 이용하여 수행하고 이 결과로부터 $^{134}$ Cs/$^{137}$Cs 와 $^{154}$ Eu/$^{137}$Cs 의 핵종비를 측정하였다. 이와 별도로 사용후핵연료의 연소도, 냉각시간, 초기농축도등에 따른 $^{134}$ Cs/$^{137}$Cs 와 $^{154}$ Eu/$^{137}$Cs의 핵종비를 ORIGEN-S 코드로 계산을 하였으며, 이 핵종비와 연소도 사이의 관계를 회귀분석하여 2차 다항식 함수로 유도하였다 이관계식과 감마선 분광실험으로 측정한 $^{134}$ Cs/$^{137}$Cs와 $^{154}$ Eu/$^{137}$Cs 의 핵종비를 이용하여 각각의 연소도를 결정할 수 있었다.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.409-409
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• 2001

• Journal of the Mineralogical Society of Korea
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• v.17 no.3
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• pp.235-243
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• 2004

Illite has been known to adsorb Cs preferentially to other alkali cations, especially at lower Cs concentration due to the frayed edge site. This frayed edge site was only verified by isotherm experiments, but not by other analytical methods. To investigate the Cs sorption properties on the surface of illite, artificially weathered illite with increasing frayed edge sites was reacted with Cs at different solution concentrations. The illite was weathered f3r 1 hour, 2 days, 14 days in 0.001 M HCl solution. With increasing reaction time, increasing amount of K in solution was observed, indicating formation of frayed edges by weathering, which was also verified by XRD, SEM, and TEM analysis. Original and weathered illites were converted to the homoionic Na form and reacted with $10^{-3}$ / ～ $10^{-7}$ M CsCl solutions for 24 hour. The aspect of Cs sorption was clearly distinguished around $10^{-5}$ M Cs concentration. The relative Cs amount sorbed on illite at low concentration (<10$^{-5}$ M) was higher than high concentration and increased with decreasing Cs concentration. In general, the amount of sorbed Cs increases with increasing weathering time and this trend is more noticeable at lower concentration while not much differentiated with weathering time at high concentration. These results indicate that the selective Cs sorption site exists in illite at low concentration, known as frayed edge site, and the number of those sites increases with weathering time.

• Journal of Korean Society for Quality Management
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• v.49 no.3
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• pp.421-431
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• 2021

Purpose: For improving outgoing quality, this study presents a novel sampling framework based on predictive analytics. Methods: The proposed framework is composed of three steps. The first step is the variable selection. The knowledge-based and data-driven approaches are employed to select important variables. The second step is the model learning. In this step, we consider the supervised classification methods, the anomaly detection methods, and the rule-based methods. The applying model is the third step. This step includes the all processes to be enabled on real-time prediction. Each prediction model classifies a product as a target sample or random sample. Thereafter intensive quality inspections are executed on the specified target samples. Results: The inspection data of three Samsung products (mobile, TV, refrigerator) are used to check functional defects in the product by utilizing the proposed method. The results demonstrate that using target sampling is more effective and efficient than random sampling. Conclusion: The results of this paper show that the proposed method can efficiently detect products that have the possibilities of user's defect in the lot. Additionally our study can guide practitioners on how to easily detect defective products using stratified sampling

• English Language & Literature Teaching
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• v.17 no.3
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• pp.99-118
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• 2011

Research on strategic Code-Switching (CS) of second language learners in teaching English in English (TEE) program provides an elaborate framework for analyzing how learners manage to express themselves in spite of their limited knowledge of the target language. This research presupposes that L2 learners' CS presents innovative solutions for communicative strategy, and that CS used as communicative strategy can promote L2 learners' language acquisition. The major questions of current research involve examining the significant patterns of different functions of CS in L2 learners' interaction and investigating L2 learners' CS styles according to the different functions of CS. The implication of CS utility is regarded as a teaching technique in the TEE program. Recorded transcript is analyzed to trace the same pattern and the categorization of CS as well as to recognize the functions of CS and their ratio. Hence, this leads to the conclusion that learners' negotiation between code selection and communication intention occurs in patterns. The learners' CS tends to be predictable, reproductive, and systematic, as one of the language acquisition phases. Therefore, the attention to the CS in the TEE program should be redirected in communication substantiality toward the principles of pragmatics. As an additional advantage of the CS analysis, this research elaborates on a conceptual acceptance of CS as a set of learners' strategies in the TEE program.

• Korean journal of food and cookery science
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• v.22 no.2 s.92
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• pp.131-139
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• 2006

This study investigated the effect of a coaching system(CS) on the employee's job satisfaction(JS) between the food service industry conducting and not conducting CS. A total of 342 employees were enrolled and the results were as follow. Firstly, relationship and willingness factors directly affected JS. Indirectly, work and relationship factors affected JS through the willingness factors. Secondly, when JS was compared at the service company conducting CS with that not conducting CS, work and relationship factors directly affected JS in the industry conducting CS, but only the relationship factor indirectly affected JS in the company not conducting CS. In addition, at the food service industry conducting CS, work factor affected willingness and competence factors, and therefore JS was affected indirectly, but relationship factor did not affect the willingness and competence factors. However, in the company not conducting CS, willingness only affected JS indirectly. Work factors directly affected JS, but through competence and willingness factors, work factor indirectly affected JS in the industry conducting CS. In the company not conducting CS, the relationship factor between employees affected the JS. In summary, CS increased JS through its direct effect on the work factor and indirect effect on the willingness and competence factors. Studies about CS are insufficient and CS remains in the introductory stage now, so further studies are necessary.