• 대한화학회지
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• 제36권5호
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• pp.692-696
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• 1992

$NH_4^+형 양이온 교환수지와 희토류-EDTA 용리액을 사용하여 희토류 원소 혼합물에서 원하는 한 원소를 분리 회수하는 연구를 하였다. NH_4^+형 양이온 교환수지에 희토류 혼합물을 흡착시키고, La-EDTA 용액으로 용리하면 수지에 흡착된 희토류 원소중 La^{3+} 이온 외의 희토류 원소는 용리된다. 수지에 남아있는 La^{3+}은 EDTA 용리액으로 용리하여 분리한다. Ce^{4+}만 선택적으로 분리하고자 할때는 La-EDTA 대신 Ce-EDTA로 용리하고 수지에 남은 Ce^{4+}을 EDTA로 용리하면 된다. 이때 분리 구조는 다음과 같다. 흡착과정 : 3RNH_4 ＋ Ln^{3+} = R_3Ln ＋ 3NH^{4+}, La-EDTA 용리 : R_3Ln ＋ La-Y- = R_3La ＋ Ln-Y^-, EDTA 용리 : R_3La ＋ HY^3- = La-Y ＋ RH ＋ 2R-.$

• 산업기술연구
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• 제21권A호
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• pp.257-261
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• 2001

The separation of rare earths minerals is very difficult because of their similar chemical properties. The rare earth minerals are used as the mixed rare earth minerals or the misch metal without separation to each element. However, the high purity rare earths are recently produced commercially to each element so they there are used as the materials for high tech. Based on the characterization results for the raw minerals, we have developed a combined process containing gravity seperation, magnetic seperation and flotation. The result obtained from this study is monazite concentration of TREO grade 69.11% and Recovery 56.02%.

• 한국세라믹학회지
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• 제37권1호
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• pp.33-43
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• 2000

Up-conversion of rare-earth element added glass is promising area for short wavelength laser source by utilizing high power semiconductor infra-red laser if the efficiency can be increased by proper method. In this study, relatively low phonon energy fluoride glasses were prepared by co-doping rare-earth elements to realize the high efficiency up-convertor. The physical, chemical, andoptical properties of co-doped fluoride glasses were measured. 10 combinations of 5 different rare-earth fluoride elements doped samples were prepared and their transition temperatures, chemical durability, density, hardness, refractive index, absorption, fluorescence, and fluorescence lifetime were measured. 480nm wavelengths blue up-conversion was found in the Yb3+/Tm3+ co-doped glass sample with 800nm laser source and the optimum composition for the most efficient blue up-conversion was found from the glass sample with 0.3 mol% TmF3 and 1 mol% YbF3.

• 암석학회지
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• 제23권4호
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• pp.337-349
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• 2014

ICP-MS를 이용한 화강암질 암석내 희토류원소의 함량 분석시 저어콘이 미치는 영향과 저어콘의 산 분해 정도를 미국지질조사소(USGS)의 화강섬록암 표준시료 GSP-2와 일본지질조사소(GSJ) 화강암 표준시료 JG-1a를 이용하여 조사하였다. 아울러 화강암에서 분리된 저어콘 광물에 대해 일반적인 산분해법과 압력용기(bomb)을 이용한 산분해법을 적용하여 지르코늄(Zr)과 희토류원소의 함량을 측정하였다. 실험결과에 의하면, 저어콘은 일반 산분해의 경우 50% 정도가 산분해된 것으로 나타났고, 압력용기를 이용한 경우에는 약 90% 전후가 분해된 것으로 확인되었다. 그리고 GSP-2와 JG-1a의 경우 추천값에 비해 지르코늄의 함량이 50% 정도인 것으로 나타났다. 이는 일반적인 화강암의 산분해의 경우 저어콘의 용해도가 실제로는 50% 정도 밖에 되지 않음을 지시한다. 하지만, 화강암내 희토류원소의 함량의 경우, 저어콘의 분해도와 상관없이, 추천값과 거의 일치하였다. 이는 저어콘의 불완전분해가 암석시료에서의 희토류원소 분포도를 이용한 암석학적 혹은 지구화학적 해석에 큰 영향을 주지는 않는다는 것을 지시해준다.

• 자원리싸이클링
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• 제27권3호
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• pp.48-57
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• 2018

본 연구에서는 폐 영구자석 스크랩에 함유된 희토류원소(Rare Earth Element, R.E.)를 첨가하여 고강도 회주철의 제조 방법을 검토하였다. 폐 영구자석 스크랩에 함유되어있는 희토류원소가 회주철의 응고 시 복합유화물 및 A형 흑연 형성을 촉진하여 조직 및 기계적 특성 향상에 효과적으로 작용한 것으로 나타났다. 폐 영구자석 스크랩을 접종제로 활용하여 주조 시 인장강도는 306 MPa의 우수한 특성으로 나타났으며, 고가의 희토류원소를 사용하여 접종한 실험의 인장강도와 비슷한 수준의 특성이다. 연구결과를 토대로 고특성의 회주철 제조에 있어서 폐 영구자석 스크랩을 활용한 R.E. 첨가가 효과적인 접종방안임을 확인하였다.

• 한국분말재료학회지
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• 제25권2호
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• pp.165-169
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• 2018

Rare earth elements (REEs) are considered to be vital to modern industry due to their important roles in applications such as permanent magnets, automobile production, displays, and many more. The imbalance between demand and supply of REEs can be solved by recycling processes. Regarding the needs of industry and society, the International Organization for Standardization, Technical Committee 298 (ISO/TC298) Rare Earths has been recently launched for developing international standards on rare earth elements. In accordance with the suggestion of its constituents, it is tentatively working to develop the appropriate standards under five working groups (WG) on terms and definitions (WG1), element recycling (WG2), environmental stewardship (WG3), packaging, labelling, marking, transport, and storage (WG4), and testing analysis (WG5). The scope and structure of ISO/TC298 on the topic of rare earths is discussed in this document.

• 분석과학
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• 제8권4호
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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%.

• Nuclear Engineering and Technology
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• 제50권6호
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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.

• Corrosion Science and Technology
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• 제17권1호
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• pp.1-5
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• 2018

As structural materials, magnesium (Mg) alloys have been widely used in the fields of aviation, automobiles, optical instruments, and electronic products. There are few studies on the effect of coating conditions on the compositional variation during the formation process of the conversion coatings. Rare-earth based conversion coating on AZ91 magnesium alloy was prepared in ceric sulfate and hydrogen peroxide contained solution. The element composition and valence as well as their distribution in the coating were analyzed with energy dispersive X-ray spectroscopy (EDS), Electron probe micro-analyzer (EPMA), X-ray photoelectron spectroscopy (XPS). The effect of treating process on the element composition were also studied. It was found that the conversion coating surface consists of Mg, Al, O, Ce, and the weight content of Ce in the coating was affected by the treating solution concentration and immersion time; the Ce element was distributed in the coating non-uniformly and existed in the form of $Ce^{+3}$ and $Ce^{+4}$, while the O element existed in the form of $OH^-$, $O^{2-}$, $H_2O$. Based on microscopic analysis results, the electrochemical deposition mechanism on the micro-anode and micro-cathode in the process of the coating growth was suggested.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.121-129
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• 2008

본 논문에서는 페라이트자석을 사용하고 있는 BLDC 전동기를 희토류 자석을 사용하는 전동기로의 설계를 다루고 있다. 최근 전기기기가 소형 경량화 됨에 따라 자석 성능이 우수한 희토류 자석을 이용한 전동기가 많이 사용되고 있다. 그러나 전기제품 메이커들은 기존의 설계를 유지하려는 경향이 있다. 본 연구에서는 전기기기에 취부되는 전동기의 외형을 그대로 하고 내부의 설계만 희토류 자석으로 변경하는 설계를 한다. 설계를 간단히 하기 위해 유한 요소법의 상용 패키지를 반복적으로 사용하였고 코깅 토오크를 줄이기 위해 고정자 요크와 고정자 단의 그루브를 설계하였다.