• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4106-4113
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• 2021

Rare earth doped barium tellurite glasses were synthesised and explored for their radiation shielding applications. All the samples showed good thermal stability with values varying between 101 ℃ and 135 ℃ based on dopants. Structural properties showed the dominance of matrix elements compared to rare earth dopants in forming the bridging and non-bridging atoms in the network. Bandgap values varied between 3.30 and 4.05 eV which was found to be monotonic with respective rare earth dopants indicating their modification effect in the network. Various radiation shielding parameters like linear attenuation coefficient, mean free path and half value layer were calculated and each showed the effect of doping. For all samples, LAC values decreased with increase in energy and is attributed to photoelectric mechanism. Thulium doped glasses showed the highest value of 1.18 cm^-1 at 0.245 MeV for 2 mol.% doping, which decreased in the order of erbium, holmium and the base barium tellurite glass, while half value layer and mean free paths showed an opposite trend with least value for 2 mol.% thulium indicating that thulium doped samples are better attenuators compared to undoped and other rare earth doped samples. Studies indicate an increased level of thulium doping in barium tellurite glasses can lead to efficient shielding materials for high energy radiation.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.413-422
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• 2019

The purpose of this study is to analyze the purchase intention of outdoor products for 40s - 50s consumers The factors influencing the purchase intention are various factors, but the service quality and the consumption value are analyzed from an exploratory viewpoint. The quality of service was set as detailed, tangibles, responsiveness, and reliability. Consumption value was set as functional value, rare value, and conditional value. As a result, tangibles, responsiveness, and reliability of the service quality, the functional value influences the purchase intention, but the rare value and the conditional value of the consumption value indicate the purchasing intention. The result of this analysis shows that service quality is a very important factor for consumers' purchase intention in 40's - 50's consumers, but consumption value is not very important factor in purchase intention.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.4
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• pp.618-630
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• 2013

This study investigates the influence of consumption value on attitude and the repurchase intention of secondhand fashion goods. In addition, this study examines the effect of consumption value on attitudes according to self-confidence in fashion coordination. Questionnaire data from 220 university students who made purchases of secondhand fashion goods were analyzed. The results were as follows. First, there were 5 factor solutions for the consumption value of secondhand fashion goods: rare value, emotional value, functional value, social contribution value, and economic value. Second, rare value, social contribution value and economic value had a positive impact on the attitude toward secondhand fashion goods. Third, attitude had positive impact on the repurchase intention of secondhand fashion goods. Fourth, there was a significant difference in the magnitude of the effect of consumption value on attitude according to self-confidence in fashion coordination. The results of this study provide various guidelines for marketers or retailers who are interested in secondhand fashion goods.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2732-2736
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• 2011

In pH 4.2 HAc-NaAc buffer solution, horseradish peroxidase (HRP) catalyzed $H_2O_2$ oxidation of nanosilver to form $Ag^+$. After centrifugation, $Ag^+$ in the supernatant can be measured by graphite furnace atomic absorption spectrophotometry (GFAAS) at the silver absorption wavelength of 328.1 nm. When HRP concentration increased, the $Ag^+$ concentration in the supernatant increased, and the absorption value enhanced. The HRP concentration in the range of 0.84-50 $ng{\cdot}mL^{-1}$ was linear to the enhanced absorption value (${\Delta}A$), with a regression equation of ${\Delta}A$=0.012C+0.11, correlation coefficient of 0.9988, and detection limit of 0.41 $ng{\cdot}mL^{-1}$ HRP. The proposed GFAAS method was used to detect HRP in waste water samples, with satisfactory results.

• Journal of Korea Trade
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• v.27 no.2
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• pp.96-114
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• 2023

Purpose - This paper elucidates a nexus between the occurrence of rare disaster events and the volatility of economic growth by distinguishing the likelihood of rare events from stochastic volatility. We provide new empirical facts based on a quarterly time series. In particular, we focus on the role of financial liberalization in spreading the economic crisis in developing countries. Design/methodology - We use quarterly data on consumption expenditure (real per capita consumption) from 44 countries, including advanced and developing countries, ending in the fourth quarter of 2020. We estimate the likelihood of rare event occurrences and stochastic volatility for countries using the Bayesian Markov chain Monte Carlo (MCMC) method developed by Barro and Jin (2021). We present our estimation results for the relationship between rare disaster events, stochastic volatility, and growth volatility. Findings - We find the global common disaster event, the COVID-19 pandemic, and thirteen country-specific disaster events. Consumption falls by about 7% on average in the first quarter of a disaster and by 4% in the long run. The occurrence of rare disaster events and the volatility of gross domestic product (GDP) growth are positively correlated (4.8%), whereas the rare events and GDP growth rate are negatively correlated (-12.1%). In particular, financial liberalization has played an important role in exacerbating the adverse impact of both rare disasters and financial market instability on growth volatility. Several case studies, including the case of South Korea, provide insights into the cause of major financial crises in small open developing countries, including the Asian currency crisis of 1998. Originality/value - This paper presents new empirical facts on the relationship between the occurrence of rare disaster events (or stochastic volatility) and growth volatility. Increasing data frequency allows for greater accuracy in assessing a country's specific risk. Our findings suggest that financial market and institutional stability can be vital for buffering against rare disaster shocks. It is necessary to preemptively strengthen the foundation for financial stability in developing countries and increase the quality of the information provided to markets.

• Resources Recycling
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• v.28 no.6
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• pp.26-35
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• 2019

This study aims to introduce and economical review on the possibilities of rare earth elements(REEs) recovery from coal ashes and the analysis of economical evaluation factors based on the data for securing domestic rare earth elements. The cut-off grade of REEs on recovering from coal ash was confirmed to be 1,000 ppm on total rare earth oxides(TREO) basis, and while the economic value of coal ash changed with contents and specific elements of rare earth elements. This shall be resulted in the price differences of rare earth elements required by the current industry, and it probably varies depending on the future demand of rare earth components. For developing of commercial recovery technology on REEs in coal ashes, many researches have been carried out by various analyzing methods, such as evaluation of holding value of REEs in ashes, assessment between supply and demand of industry, comparison of investment and its profitability for the REEs's production from coal ashes, and so on. Although these methods have been suggested, its recovery system with economical feasibility could not been confirmed up to present. In this reason, the process design of recovering REEs from coal ash shall be researched continuously to solve the problems of the global rare earth market. And also these researches shall be conducted actively in Korea for the purpose of securing the REEs resources and their recovering technologies.

• The Journal of the Petrological Society of Korea
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• v.14 no.4 s.42
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• pp.237-250
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• 2005

In order to clarify the effect of standard rock material in the chemical analysis of rare earth element abundance with ICP-MS, we measured rare earth element abundance of KIGAM granite standard rock material (KG-1), USGS granite standard rock material (G-2), GSJ granite standard rock materials (JG-1a and JG-2). In REE analysis, we used conventional calibration standard solutions, KG-1, JG-1a, JG-2 and G-2 as standard material, respectively. Chondrite-normalized LREE patterns of low granite standard material correspond well each other in the recommended value and the estimated value regardless of a kind of standard rock. However, the HREE patterns of the estimated value based on G-2 or JG-2 and the recommended value are different from each other. Such difference may be due to the wrong recommended value or a specific geochemical properly of the standard rock material itself, The chondrite-normalized REE patterns of four standard rock materials estimated on the basis of KG-1 or JG-1 a show little deviation compared to the those of the recommended values. This suggests that KG-1 and JG-1a may be a optimum standard material for granitoids.

• Journal of Environmental Impact Assessment
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• v.6 no.2
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• pp.153-164
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• 1997

This study was conducted to develop the new Environmental Impact Assessment techniques for the grading of rareness in plant. 17 EISs which were submitted in 1996 were analyzed to know the problems in existent EIA techniques for the conservation of rare plants. Category of rare plant was reevaluated and evaluation technique for the grading of rareness in plant was developed. The results obtained from this study were as follows: 1. The evaluation technique of rareness in plant was not reflected in the current preparation provision for EIS. And t his fact also appeared in most of the EIS which were reexamined in this study. 2. The category of rare species which have been considered as the subject of protection in EIA have to be enlarged to more than legally protected species designated by MOE. 3. The taxonomic characteristics and status of species, characteristics of population, geographical characters, extent of threat and its possibility by man resulted from the habitat loss were investigated. Each item was endowed scores from 1 to 5 and all the scores were summed, and then this value was used to evaluate the order of conservation. 4. Conservation measures for the rare plants have to be applied according to the levels of rareness grade, and they are absolute conservation, in situ conservation, transplanting and ex situ conservation, post observation and none by the levels from A to E. 5. Considering the phenology of rare plants, investigation for the rare plants have to be made a1 least three times. 6. Size of the MVP(Minimum Viable Population), pollination ecology also have to be considered for the conservation of rare plants. And in the case of adopting ex situ conservation measure, the site and methods for the conservation of rare plants have to be proposed in detail.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.538-548
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• 2003

We studied effects by Re$_2$O$_3$(R=Dy, Gd, Ho) addition on the properties of Mn-Zn ferrite. The doping concentration range from 0.05 wt% to 0.25 wt%. All samples were prepared by standard fabrication of ceramics. With increasing the rare earth oxides, specific density and initial permeability increased on the whole. But, the tendencies such as upper result had the measured value on limitation and characteristics saturated or decreased properties after that. In case of excessive addition of additive beyond some level, initial permeability properties of ferrite have gone down in spite of anomalous grain. With increasing the content of additive, both the real and imaginary component of complex permeability and the magnetic loss (tan$\delta$) increased. Because the increased rate of real component had higher than imaginary component, magnetic loss increased none the less for increasing the real component related with magnetic permeability. But, the magnetic loss of ferrite doped with the rare earth oxides was lower than that of Mn-Zn ferrite at any rate. The small amount of present rare earth oxides in Mn-Zn ferrite composition led to enhancement of resistivity in bulk, and more so in the grain boundary. It was seem to be due to the formation of mutual reaction such as between iron ions and rare earth element ions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.887-894
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• 2000

In this paper, we have studied the effect of earth (Gd, Er) on the various properties (microstructure, shrinkage, initial permeability, permeability as a function of frequency, etc) of Ba-ferrite. The permeabilities were analyzed by Impedance Analyzer(100KHz~40MHz) and Network Analyzer(30KHz~3㎓). As the result of XRD, all of the Ba-ferrite doped with rat earth was found to be Y-hexagonal phase. The resonance frequencies at the maximum imaginary value of complex permeability were observed near 2㎓. The complex permeabilities of the Ba-ferrite doped with Gd$_2$O$_3$at 3wt% and doped with Er$_2$O$_3$at 3wt% and 5wt% as a function of frequency showed the highest value at sintered temperature at 95$0^{\circ}C$/3h.