• Ocean and Polar Research
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• v.25 no.1
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• pp.53-62
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• 2003

Inductively coupled plasma mass spectrometry (ICP-MS) is useful instrument for determining abundance of rare earth elements, due to very low detection limits and rapid data acquisition. In this article, two methods are used for decomposition of alkaline rocks; close vessel acid digestion and $Na_2Co_3$ fusion. The two analytical results show good agreements. Considering total dissolved solids and detection limits, the most adequate dilution factor is 5,000 times. Polyatomic ion interferences during analysis can give rise to Inaccuracies. After correction from oxide and hydroxide interference, the analytical result show 20-30% decrease for Gd and Tm, 10-20% decrease for Tb and Er. In comparing the analytical results from KORDI with other institutes, most rare earth elements abundance show good agreements except Lu.

• Journal of radiological science and technology
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• v.1 no.1
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• pp.15-24
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• 1978

The characteristics of the rare earth phosphors intensifying screen (LM-6, Grenex-8) as compared with $CaWO_4$ intensifying screen had been studied utilizing several common x-ray films, and found the following results. 1. Compared with the conventional CaWO4 intensifying screen, the rare earth phosphors intensifying screen was found to be more sensitive over to 1.26-3.47 times. So the radiation exposure could be reduced to 1/1.26 -1/3.47. 2. Sharpness as well as the film speed were both increased. So the motion blurring and geometrical unsharpness could be decreased. 3. In spite of that the film speed was increased, photographic contrast was kept up. Therefore, the more ideal film of greater latitude could be obtained. 4. The effects of the rare earth phosphors intensifying screen would be much increased as using with orthochromatic x-ray films.

• Communications for Statistical Applications and Methods
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• v.11 no.1
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• pp.181-187
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• 2004

One of objectives in epidemiologic studies is to detect the amount of change caused by a specific risk factor. Risk ratio is one of the most useful measurements in epidemiology. When we perform the inference for this measurement with rare events, the standard approach based on the normal approximation may fail, in particular when there are no disease cases observed. In this paper, we discuss and evaluate several existing methods for constructing a confidence interval of risk ratio through simulation when the disease of interest is a rare event. The results in this paper provide guidance with how to construct interval estimates for risk difference and risk ratio when there are no disease cases observed.

• The Korean Journal of Applied Statistics
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• v.25 no.3
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• pp.435-446
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• 2012

Epidemiologic studies frequently try to estimate the impact of a specific risk factor. The risk difference and the risk ratio are generally useful measurements for this purpose. When using such measurements for rare events, the standard approaches based on the normal approximation may fail, in particular when no events are observed. In this paper, we discuss and evaluate several existing methods to construct confidence intervals around risk differences and risk ratios using Monte-Carlo simulations when the disease of interest is rare. The results in this paper provide guidance how to construct interval estimates of the risk differences and the risk ratios when no events are detected.

• Applied Microscopy
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• v.45 no.2
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• pp.44-51
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• 2015

At room temperature, metallic glasses deform inhomogeneously by strain localization into narrow bands as a result of yielding due to an external force. When shear bands are generated during deformation, often nanocrystals form at the shear bands. Experimental results on the deformation of bulk metallic glass in the current study suggest that the occurrence of nanocrystallization at a shear band implies the loading condition that induces deformation is more triaxial in nature than uniaxial. Under a compressive stress state, the geometrical constraint strain imposed by the stress triaxiality plays a crucial role in the deformation-induced nanocrystallization at the shear bands.

• Fisheries and Aquatic Sciences
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• v.17 no.3
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• pp.339-344
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• 2014

PCR amplification with universal primer is a useful tool for speciation of symbionts in marine eukaryote coupled with robust separation method such as denaturing high performance chromatography (DHPLC). To overcome the biased amplification, clamping PCR is recommended to suppress the amplification of host gene. In this study, we evaluated the efficiency of rare gene detection for two kinds of clamping probes which were successfully utilized for eukaryotic symbiont analysis: C3 linked nucleotide (C3) and peptide nucleic acid (PNA). PNA was 3-4 orders of magnitude higher than that of C3 tested in clamping efficiency and rare gene detection. This represented that PNA could be a more competent clamping probe for the enhancement of PCR amplification for rare symbiont genes.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.434-437
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• 2007

Maps contain and effectively visualize a number of spatial information. Advances in GIS enable researchers to analyze and represent spatial information through digital maps. Choropleth maps represent different quantities showing usually rates, percentages or densities. Generally, researchers make choropleth maps using raw rates. But, if the events are rare, raw rates cannot be sufficient in representing spatial phenomena. That is to say, if the population is large and events are rare, we cannot be sure that the raw rate is correct. The objective of this study is to make choropleth maps by several rate calculation methods and compare them. We use three methods in choropleth mapping; a raw rate, empirical Bayesian method, and spatial rate method which use prior probabilities. The experiments reveal that maps are somewhat different by used methods. We suggest that a raw rate method can not be an only way to make a rate map and researchers should choose an appropriate method for their objectives.

• Journal of Applied Biological Chemistry
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• v.60 no.3
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• pp.207-211
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• 2017

It is introduced an outstanding book about an important topic in occupational and environmental sciences i.e., the opportunities and challenges that may be connected with increasing the use and distribution of rare earth elements. These chemically similar elements, comprising the lanthanides, scandium, and yttrium, are involved in a number of essential technological applications, and their effects raise a number of human health issues of relevance to the occupational and environmental sciences. The book that I introduced here, "Rare Earth Elements in Human and Environmental Health; At the Crossroads between Toxicity and Safety" edited by Giovanni Pagano (Pan Stanford Publishing Pte. Ltd., Temasek Boulevard, Singapore) represents a break from that situation. It is essential to increase our knowledge about the environmental fate and biological effects of these technologically important metals in order to prevent unforeseen long-term man-made consequences to human health. This book is likely to become an important resource for scientists, engineers, and decision makers who understand the need for sensible exploitation of this resource.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.663-672
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• 2007

The mutual separation behavior of actinides and rare earths in a countercurrent multistage reductive extraction system was predicted by computer calculation. The distribution information for actinides and rare earths in the reductive extraction systems of LiCl-KCl/Cd and LiCl-KCl/Bi was collected from literature and then it was used for the calculation of a multistage extraction. The results of the concentration profiles throughout the extraction cascade, recovery yields of various metal solutes, and separation factors between the actinides and rare earths were calculated. The effects of the major process parameters, such as reducing agent content in the metal phase, number of stages, and salt/metal flow ratio, etc., on the extraction behavior were also examined.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.790-791
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• 2006

The fracture behavior and mechanical characteristics of sintered rare-earth magnets were investigated. It shows that the fracture behavior and bending strength of the magnets obviously exhibit anisotropy. Sm-Co magnets tend to cleavage fracture in the close-packed (0001) plane or in the ($10\bar{1}1$) plane. The fracture mechanism of $Nd_2Fe_{14}B$ magnet mainly appears to be intergranular fracture. The anisotropy of fracture behavior and mechanical strength of sintered rare-earth magnets is caused mainly by the strong crystal-structure anisotropy and the grain alignment texture. The effects of Nd content, and Pr, Dy substitution on the impact stability of $Nd_2Fe_{14}B$ magnets were also reported.