• Economic and Environmental Geology
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• v.56 no.2
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• pp.125-138
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• 2023

Most of previous cesium (Cs) sorbents have limitations on the treatment in the large-scale water system having low Cs concentration and high ion strength. In this study, the new Cs sorbent that is eco-friendly and has a high Cs removal efficiency was developed by improving the coal mine drainage treated sludge (hereafter 'CMDS') with the addition of Na and S. The sludge produced through the treatment process for the mine drainage originating from the abandoned coal mine was used as the primary material for developing the new Cs sorbent because of its high Ca and Fe contents. The CMDS was improved by adding Na and S during the heat treatment process (hereafter 'Na-S-CMDS' for the developed sorbent in this study). Laboratory experiments and the sorption model studies were performed to evaluate the Cs sorption capacity and to understand the Cs sorption mechanisms of the Na-S-CMDS. The physicochemical and mineralogical properties of the Na-S-CMDS were also investigated through various analyses, such as XRF, XRD, SEM/EDS, XPS, etc. From results of batch sorption experiments, the Na-S-CMDS showed the fast sorption rate (in equilibrium within few hours) and the very high Cs removal efficiency (> 90.0%) even at the low Cs concentration in solution (< 0.5 mg/L). The experimental results were well fitted to the Langmuir isotherm model, suggesting the mostly monolayer coverage sorption of the Cs on the Na-S-CMDS. The Cs sorption kinetic model studies supported that the Cs sorption tendency of the Na-S-CMDS was similar to the pseudo-second-order model curve and more complicated chemical sorption process could occur rather than the simple physical adsorption. Results of XRF and XRD analyses for the Na-S-CMDS after the Cs sorption showed that the Na content clearly decreased in the Na-S-CMDS and the erdite (NaFeS₂·2(H₂O)) was disappeared, suggesting that the active ion exchange between Na⁺ and Cs⁺ occurred on the Na-S-CMDS during the Cs sorption process. From results of the XPS analysis, the strong interaction between Cs and S in Na-S-CMDS was investigated and the high Cs sorption capacity was resulted from the binding between Cs and S (or S-complex). Results from this study supported that the Na-S-CMDS has an outstanding potential to remove the Cs from radioactive contaminated water systems such as seawater and groundwater, which have high ion strength but low Cs concentration.

• Journal of Environmental Science International
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• v.24 no.2
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• pp.151-162
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• 2015

The adsorption characteristics of Sr ions and Cs ions in single and binary solution by zeolite A were investigated in batch experiment. The adsorption rate of Sr ions and Cs ions by zeolite A obeyed pseudo-second-order kinetic model in single and binary solution. The initial adsorption rates (h) and adsorption capacities of both ions obtained from pseudo-second-order kinetic model, and the values were decreased with increasing concentration of the competitive ions (0~1.5 mM). Also, adsorption isotherm data in binary solution were well fitted to the extended Langmuir model, the maximum adsorption capacities of Sr and Cs calculated from the model were 1.78 mmol/g and 1.64 mmol/g, respectively. The adsorption of Sr and Cs ions by zeolite A was carried out in the presence of other cations such as $Na^+$, $K^+$, $Mg^{2+}$ and $Ca^{2+}$. The results showed that the zeolite A can maintain a relatively high adsorption capacity for Sr and Cs ions and exhibits a high selectivity in the presence of competitive cations. The effect of competition had an order of $Ca^{2+}$ > $K^+$ > $Mg^{2+}$ > $Na^+$ for Sr ions and $K^+$ > $Ca^{2+}$ > $Na^+$ > $Mg^{2+}$ for Cs ions at the same cation concentration.

• Proceedings of the Korean Society for Quality Management Conference
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• 2010.04a
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• pp.291-309
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• 2010

Customer satisfaction is an ever-growing concern of management throughout the world. To find the way to increase customer satisfaction, we must understand customer requirements. Kano distinguishes between three types of product requirements(must-be, one-dimensional, attractive requirement) which influence customer satisfaction in different ways when met. Timko has developed customer satisfaction(CS) coefficient based on Kano model. The CS coefficient is indicative of how strongly a product feature may influence satisfaction. In this paper, potential customer satisfaction improvement(PCSI) index was developed using Kano model and CS coefficient. The PCSI index represents how much a product feature can increase the degree of customer satisfaction when the product feature is fully fulfilled. In order to explain the meaning of PCSI index, a case study for cellular phones is done. It is also discussed how to use the index strategically.

• Journal of Korean Society for Quality Management
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• v.38 no.2
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• pp.248-260
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• 2010

Customer satisfaction is an ever-growing concern of management throughout the world. To find the way to increase customer satisfaction, we must understand customer requirements. Kano distinguishes between three types of product requirements (;must-be, one-dimensional, attractive requirement) which influence customer satisfaction in different ways when met. Timko has developed customer satisfaction(CS) coefficient based on Kano model. The CS coefficient is indicative of how strongly a product feature may influence satisfaction. In this paper, potential customer satisfaction improvement(PCSI) index was proposed using Kano model and CS coefficient. The PCSI index represents how much a product feature can increase the degree of customer satisfaction when the product feature is fully fulfilled. In order to explain the meaning of PCSI index, a case study for cellular phones is done. It is also discussed how to use the index strategically.

• Journal of Radiation Protection and Research
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• v.17 no.2
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• pp.15-23
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• 1992

Transport behaviors of Cs-137 and Sr-90 were analyzed and ingestion doses were calculated using dynamic model for rice field-rice-man pathway. Cs-137 binding strongly to soil remain longer in rice field than Sr-90. Foliar deposition on rice plant during growing period is the main contamination mechanism.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1331-1341
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• 2015

The removal of Sr ion and Cs ion was investigated to evaluate adsorption properties by using SAN-Zeolite beads immobilized with styrene acrylonitrile (SAN). The adsorption capacities increased with the decrease of SAN/zeolite ratio (SAR) from 2.5 to 0.83. The relationship of adsorption capacity ($q_e$) and SAR was described by experimental equation such as $q_e=20.88+137.81e^{-1.96SAR}$ ($r^2=0.9980$). The adsorption kinetics of Sr ion and Cs ion with SAN-Zeolite beads were fitted well by the pseudo-second-order model. The maximum adsorption capacities of Sr ion and Cs ion calculated from Langmuir isotherm model were 66.97 mg/g and 81.97 mg/g, respectively.

• Asia Marketing Journal
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• v.10 no.1
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• pp.1-23
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• 2008

It is natural that firms would like to increase their profits and value through customer satisfaction (CS). It is therefore important for the academic and practical purposes to investigate the relationship between CS and firm's performance. Previous studies about this relationship have examined mainly the current effect of CS on firm's performance. According to the research that many marketing activities have dynamic effects over time, however, the dynamic effect of CS on firm's performance needs to be tested. Failure to assess the dynamic effects might lead to the underestimation of the impact of CS. This study thus attempts to investigate the dynamic effects of CS on firm's profitability and value by panel data analysis. The results show that CS has dynamic effects on firm's profitability and value. There was a significant improvement in model fit compared with the model examining the current effects only. On the other hand, it was difficult to interpret the estimation results of the alternative model incorporating two lagged variables of CS, and there was also a multicollinearity problem.

• Journal of Distribution Science
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• v.14 no.11
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• pp.83-90
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• 2016

Purpose - During the last two years, convenient stores (CS) are emerging as one of the most fast-growing retail trades in Korea. The goal of this work is to forecast and to analyze sales at CS using ARIMA-Intervention model (IM) and exponential smoothing method (ESM), together with sales at supermarkets in South Korea. Considering that two retail trades above are homogeneous and comparable in size and purchasing items on off-line distribution channel, individual behavior and characteristic can be detected and also relative superiority of future growth can be forecasted. In particular, the rapid growth of sales at CS is regarded as an everlasting external event, or step intervention, so that IM with season variation can be examined. At the same time, Winters ESM can be investigated as an alternative to seasonal ARIMA-IM, on the assumption that the underlying series shows exponentially decreasing weights over time. In case of sales at supermarkets, the marked intervention could not be found over the underlying periods, so that only Winters ESM is considered. Research Design, Data, and Methodology - The dataset of this research is obtained from Korean Statistical Information Service (1/2010~7/2016) and Survey of Service Trend of Korea Statistics Administration. This work is exploited time series analyses such as IM, ESM and model-fitting statistics by using TSPLOT, TSMODEL, EXSMOOTH, ARIMA and MODELFIT procedures in SPSS 23.0. Results - By applying seasonal ARIMA-Intervention model to sales at CS, the steep and persisting increase can be expected over the next one year. On the other hand, we expect the rate of sales growth of supermarkets to be lagging and tied up constantly in the next 2016 year. Conclusions - Based on 2017 one-year sales forecasts for CS and supermarkets, we can yield the useful information for the development of CS and also for all retail trades. Future study is needed to analyze sales of popular items individually such as tobacco, banana milk, soju and so on and to get segmented results. Furthermore, we can expand sales forecasts to other retail trades such as department stores, hypermarkets, non-store retailing, so that comprehensive diagnostics can be delivered in the future.

• KIISE Transactions on Computing Practices
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• v.23 no.4
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• pp.256-261
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• 2017

The notion of System of Systems (SoS), which is composed by many independent systems (i.e., Constituent Systems, CS), has emerged in various domains including social infrastructure. It is widely expected that complex requirements, which cannot be achieved in each CS-level, will be achieved in an SoS-level. While verification of SoS-level goal achievement is one of the most important problems, concrete case studies on SoS modeling and verification are still rare. In this paper, we focus on the fact that each CS performs an action for its own purpose by its own decision-making mechanism. We propose a novel Action-Benefit-Cost (ABC) SoS model which caters to the independent decision-making mechanisms of CSs. Using an abstract SoS example, this proposal provides a case study for the modeling and quantitative verification of the ABC SoS model.

• Journal of Navigation and Port Research
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• v.48 no.5
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• pp.368-375
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• 2024

This research develops a big data-based CS model for maritime traffic assessment, motivated by global shipping growth, the impact of COVID-19, changes in consumer culture, and Industry 4.0 expansion in maritime sectors. Maritime traffic, crucial for global trade, demands effective management for safety and efficiency. This study aims to quantitatively and objectively evaluate maritime traffic smoothness by analyzing ship operation data. The CS model focuses on unique maritime characteristics, leveraging big data to enhance traffic management solutions and safety. The research methodology includes analyzing domestic and international trends and data to reflect maritime spatiality and continuity. The model's efficacy is tested through case studies on major port routes, comparing it with existing models to suggest improvements. This new approach provides a framework for optimizing maritime traffic routes and supports autonomous, unmanned, and smart ship operations, setting a new paradigm for maritime traffic management.