• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.188-193
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• 2012

Permanent magnet is one of the most important parts in modern industry and the rare earth elements play an essential role for operation of permanent magnet. As is well known, the rare earth elements are mostly produced in China and the world is now facing serious problems owing to supply and demand imbalances. Many attempts have been performed to replace these rare-earth based permanent magnets by rare-earth free magnets, but they have not been successful so far. Regarding this issue, we discuss about an exchange spring magnet as a potential rare earth free permanent magnet structure.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.915-922
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• 2018

Metallic fuel has been considered for sodium-cooled fast reactors because it can maximize the uranium resources. It generates rare earth elements as fission products, where it is reported by aggravating the fuel-cladding chemical interaction at the operating temperature. Rare earth elements form a multicomponent alloy (Ce-Nd-Pr-La-Sm-etc.) during reactor operation, where it shows a higher reaction thickness than a single element. Experiments have been carried out by simplifying multicomponent alloys for mono or binary systems because complex alloys have difficulty in the analysis. In previous experiments, xCe-yNd was fabricated with two elements, Ce and Nd, which have a major effect on the fuel-cladding chemical interaction, and the thickness of the reaction layer reached maximum when the rare earth elements ratio was 1:1. The objective of this study is to evaluate the effect and relationship of rare earth elements on such synergistic behavior. Single and binary rare earth model alloys were prepared by selecting five rare earth elements (Ce, Nd, Pr, La, and Sm). In the single system, Nd and Pr behaviors were close to diffusion, and Ce showed a eutectic reaction. In the binary system, Ce and Sm further increased the reaction layer, and La showed a non-synergy effect.

• Resources Recycling
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• v.27 no.3
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• pp.8-15
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• 2018

Solvent extraction behavior of light rare earth elements (Pr, Nd) and medium rare erath elements (Tb, Dy) in the HCl-PC88A-kerosene extraction system was investigated in order to separate high-purity light rare earths (Pr, Nd) and medium rare earths (Tb, Dy) in the mixed rare earth chloride solution. In the batch test step, it was confirmed that the separation efficiency was good when the extractant concentration (PC88A) was 0.5 M, the equilibrium pH after extraction was 0.8 to 1.0 (initial pH 1.3 of the feed), the concentrations of hydrochloric acid in scrubbing solution was set as 0.1 M, the concentrations of hydrochloric acid in stripping solution was set as 2.0 M or more. Based on the experimental data obtained from the batch test, the mixer-settler was composed as follows; 4 stages of extraction, 8 stages of scrubbing, 4 stages of stripping, and 3 stages of pickling organic solution. The Mixer-settler was operated for 180 hours, and the operating conditions were continuously adjusted to obtain the high-purity light/medium rare earths. Finally, the purity of light (Pr, Nd) and medium rare earth elements (Tb, Dy) was reached as 3 N class.

• Environmental Engineering Research
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• v.18 no.4
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• pp.211-219
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• 2013

Rare-earth manganites have a great potential for environmental applications based on their chemical and physical properties. The use of rare-earth manganites as catalysts for environmentally essential reactions was reviewed. Artificial neural networks were used to assess the catalytic activity in oxidation reactions. Relative catalytic activities of the catalysts were further discussed. We concluded that cerium manganite is the most practicable catalyst for technological purposes.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.200-203
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• 2009

One-dimensional rare earth oxide luminescence nano materials have been prepared by a combination method of sol-gel process and electrospinning. Systematic studie s on optical properties indicate that electrospinning is a facile and novel route for development luminescen ce materials that are useful in fluorescent lamps an d field emission dispalys.

• Journal of the Korean Magnetics Society
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• v.21 no.4
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• pp.147-150
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• 2011

Since their discovery in the early 1980's, the market for bonded rare earth magnets has shown steady growth. Today these magnets are widely used for our daily life such as computer peripherals, automotive, consumer electronics, and office automation. However, the price increases of rare-earths started from the $2^{nd}$ half of 2010 became even worse in 2011. During $2^{nd}$ quarter of 2011, almost all of rare-earths showed unprecedented vertical price increases, and it brought significant impact to the related industry in terms of the price and supply. This will ask the fundamental change in the policy of the bonded rare earth industry to expand its market share, which has been highly dependent on the replacement of ferrite magnets via relatively higher performance compared to the price at certain applications. In order to achieve the sustainable growth of bonded rare-earth magnets in the future, it needs to change the current paradigm and setup the new business model. This article includes a brief summary of the rare earth price trend and the applications of the rare-earth bonded magnets. The efforts to improve the performance and diversify the applications for future growth have been also presented.

• Analytical Science and Technology
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• v.14 no.4
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• pp.371-375
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• 2001

The stability constants of complexes between rare earth elements(Yb, Dy, Sm, Nd, Pr, Ce, La) and ethylenediaminediacetic acid(EDDA) have been measured for the separation of rare earth elements by potentiometric method. The $pk_1s$ of $MA^+$ complexes are in the range of 8.80-6.72 and the $pk_2s$ of $MA_2^-$ complexes are in the range of 7.43-4.37. The magnitude sequences of the stability constants are the reverse of the ionic size of rare earth elements.

• Analytical Science and Technology
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• v.8 no.4
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• pp.553-559
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• 1995

An extraction chromatographic method of separating rare earth impurities from high purity $Nd_2O_3$, $Sm_2O_3$, $Gd_2O_3$, $Er_2O_3$, $Dy_2O_3$ and $Yb_2O_3$ was studied by using $HCl-NH_4Cl$ as moving phase and P507 as stationary phase. After the impurities were enriched from the eluate by chelant-activated carbon, the active carbon was ashed and the ignited residue was used to prepare the sample electrode for spark source mass spectrometric determination. The impurities in 99.9999% rare earth oxide can be determined by the proposed method with recovery over 80%.

• Proceedings of the Korean Magnestics Society Conference
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• 2013.12a
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• pp.90-90
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• 2013

Since discovery, NdFeB permanent magnet has replaced application of the conventional magnets rapidly because of its superior physical and mechanical properties. With increasing consumption of power combined with energy resource depletion, energy efficiency is becoming more and more inportant. According to recent reports, almost almost half of the electric power is consumed by motor, and NdFeB magnets which are the core component of the motor play a key role on improving energy efficiency of the devices. In parallel with finding alternatives energy resources, research works improving energy efficiecy have been conducted world wide. Althogh NdFeB magnets usage have been expanded to various applications, key materials such as Nd and Dy, resouces lean heavily on specific area, China. Magnetic industry revently experienced skyrocketing price fluctuatioin of rare earth at around 2008. Chineses government's regulations worsened the situation and arose a necessity to develop methods to minimize rare earth use. In this presentation, POSCO's recent research works on rare earth reduction is presented including novel powder alloying method using nitrate precursors. Also, future R&D plans for rare earth free magnets is briefly introduced as well.

• Macromolecular Research
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• v.17 no.8
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• pp.563-567
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• 2009

In order to improve the thermomechanical performance of polyketone, a third monomer (4-methylstyrene) was added to the copolymerization system. The terpolymer of CO, styrene, and 4-methylstyrene was synthesized in the presence of multi component catalysts containing palladium acetate and rare earth metal phosphonates. The products were characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The effects of the different components, including the third monomer, palladium acetate, 2,2'-bipyridyl, rare earth phosphonate, p-toluene-sulphonic acid, and p-benzoquinone, were also studied. The highest catalytic activity of 965.51 g/(gPd h) was obtained with a catalyst containing palladium acetate and rare earth phosphonate.