• Journal of Radiation Protection and Research
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• v.10 no.1
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• pp.3-13
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• 1985

The sorption behavior of some typical fission products such as Cs-137, long-lived radionuclide; Ce-144, rare-earth element; and Co-60, corrosion product on zeolite A, zeolite F-9 (faujasite) and amorphous zeolite was determined with the salt concentrations, 0.01 M- to 2.0 M- nitric acid and ammonium nitrate, and the shaking time, 15 minutes interval from 15 minute to 90 minute. Kd values were obtained through the batch experiment. In conclusion, the optimal conditions for isolation and removal of the typical radionuclides are as following: zeolite, amorphous zeolite; concentration, $0.01\;M-HNO_3\;and\;0.1\;M-NH_4NO_3$; pH4; shaking time, one hour; the most effective species, Cs-137.

• Analytical Science and Technology
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• v.7 no.1
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• pp.1-10
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• 1994

A survey was made on detection limit, reproducibility, matrix effect, linear dynamic range and the memory effect of yttrium and europium in order to analyze rare earth elements which exist as impurities in the rare earth oxide which is raw materials of fluorescent substance. When analysing a certain amount of thulium quantitatively using inductively coupled plasma mass spectrometry, it was found that the analysis was interfered with $EuO^+$ which is one of polyatomic ions caused by plasma. As the intensity of thulium linearly proportional to the europium concentration, it was possible to the determine the actual concentration of thulium.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.4
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• pp.333-339
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• 1995

The reduction and diffusion process(R-D process) is an economical way to produce the functional materials which contain rare-earth elements and has been applied to the production of rare-earth magnet meterials($SmCo_5$, $Nd_{15}Fe_{77}B_8$), magneto-optical(MO) target materials and hydrogen storage alloy, etc. However, because of difficult to control of the final composition, the R-D process has not been applied to production of the 2-17 type rare earth permanent magnet materials which contain several elements. Therefore, this work was as a basic study for the production of the 2-17 type rare earth permanent materials with composition $Sm(Co_{0.72}Fe_{0.21}Cu_{0.05}Zr_{0.03})_{7.9}$ by the R-D process, the following were mainy examined ; the amount of metallic calcium as a reductant, homogenization condition of the alloy after the R-D reaction, masuring of magnetic properties of the sample after step aging. The sample prepared by the R-D process contained a little more oxygen than that prepared by the melting method, however, showed almost the same magnetic properties.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.126-129
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• 1994

In order to invetigate the effect of Pr additive on the magnetostriction of amorphous Fe-B alloys, amorphous $Fe_{86-x}B_{14}Pr_{x}(2{\leq}x{\leq}8\;at.%)$ alloys were prepared by a rapid solidification process. As the Pr content increased in the as-prepared amorphous $Fe_{84}B_{14}Pr_{2}$ alloy annealed at $300^{\circ}C$ for 2 hr increased to 70 ppm. Ac power loss and permeability$(f=50\;kHz,\;B_{m}=0.1\;T)$ of the annealed amorphous $Fe_{84}B_{14}Pr_{2}$ alloy were 15 W/kg and $5.5{\times}10^{3}$, respectively.

• Journal of the Korean Ceramic Society
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• v.32 no.10
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• pp.1178-1188
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• 1995

Bi4Ti3O12 (BIT) and its rare earth (Y, Nd, Sm, Gd)-substituted derivatives were synthesized using a sol-gel method to investigate their microstructures, cystal structures and electrical properties depending on the subsituted elemetns. Nd- or Sm-substitution into BIT appeared to be favorable, while Y- or Gd-substitution occurred with a pyrochlore phase. This suggests that a smaller trivalent rare earth ion may not be favorable in the structure of BIT. The rare earth derivatives showed that their particle sizes and shapes were considerably different depending on the kinds of substituted elements. Y-substitution resulted in developing a relatively even particle size and a dense microstructure. In structure, they may be similar to the pseudo-orthorhombic BIT but close to a paraelectric tetragonal phase. Their a (or b) axes were shortened, compared to the one of BIT. Such a distortion may result a decrease in the tilting of TiO6. BIT and the derivatives showed that their dielectric constants and losses were 40~120 and less than 0.03, respectively in the frequency range of 1~10 MHz. The dielectric loss of Y-substituted derivative was the lowest one and changed a little to frequency. Curie points were observed in all the derivatives like BIT to suggest that they would be ferroelectric. The temperature stability of the delectric properties of the derivatives below the Curie points were relatively better than the one of BIT.

• Journal of Korea Foundry Society
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• v.23 no.4
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• pp.187-194
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• 2003

The effect of rare earth elements (R.E)(from 0.0 to 0.04%) on the microstructure formation and mechanical properties of thin-wall ductile iron castings were investigated. Tensile strength and hardness were decreased with an addition of up to 0.03% rare-earth elements. After addition of more than 0.03%, those were increased. Graphite nodule sizes were the finest, nodule count was the highst regardless of thickness and volume fraction of ferrite was the largest when that was 0.02%. However, the nodule count was decreased with increasing R.E. Futhermore. nodule size increased with increasing thickness and the volume fraction of ferrite decreased as that was increased. Nodularity was increased regardless of the thickness as that was increased. The castings of minium thickness up to 3 mm was possible without the formation of chill.

• Journal of the Korean Ceramic Society
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• v.37 no.10
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• pp.1014-1020
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• 2000

RF 마크네트론 스퍼터법으로 Ce의 일부를 희토류 원소로 치환한 Ce$_{1-x}$RE$_{x}$O$_{2-y}$(0.1$\leq$x$\leq$0.4, RE=Y, Nd) 박막을 Si(111), $Al_2$O$_3$(1012) 기판 위에 1450~1$600^{\circ}C$로 소결한 target을 이용하여 성장시켰다. Ce$_{1-x}$RE$_{x}$O$_{2-y}$ 박막의 성장시 기판온도 및 증착시간 등을 변화시켜 성장시켰으며, 성장된 박막의 특성분석은 XRD, SEM, TEM으로 행하였다. 증착된 박막의 방향성 및 결정성장 거동은 증착온도 및 시간에 따라 차이를 보였다. Si(111) 기판 위에 증착된 Ce$_{1-x}$Y$_{x}$O$_{2-y}$(x=0.3) 박막의 경우, 80$0^{\circ}C$에 비해 7$50^{\circ}C$에서 증착 시간에 따른 (111) 우선배향성의 정도가 나은 결과를 보였으며, $Al_2$O$_3$(1012) 기판 위에 증착한 Ce$_{1-x}$Nd$_{x}$O$_{2-y}$(x=0.3) 박막 또는 (111) 우선배향성을 나타내었다.을 나타내었다.

• Journal of the Korean Magnetics Society
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• v.11 no.1
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• pp.8-13
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• 2001

Effects of casting Processes and lubricant addition were studied to improve remanence of 31RE-68TM-lB based sintered magnet by using axial pressing process. Strip casting was effective to get the fine and homogeneous microstructure without ${\alpha}$-Fe segregation. The strip cast flake resulted in narrower particle size distribution after jet milling with respect to the conventional cast ingot. During pressing step with a magnetic field, the particle alignment was increased by appropriate addition of liquid lubricant. In this study, it was revealed that narrow particle size distribution and appropriate addition of liquid lubricant were essential to improve the grain alignment and thus the remanence of Nd-Fe-B sintered magnet.

• Journal of the Mineralogical Society of Korea
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• v.7 no.2
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• pp.111-127
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• 1994

양남 지역의 제 3 기층인 하서리 응회암층의 중.상부에 부존되는 벤토나이트들은 원암의 암상과 화학조성에 의존되는 광호 양상과 광물상을 나타낸다. 벤톤나이트들은 대부분 안산암질 원암의 기원을 시사하는 희유 및 희토류 원소들의 함유 양상을 보이고, 현무암질 원암의 벤토나이트는 최상부의 일부 층준에만 그 산출이 국한된다. 이 지역의 벤토나이트는 주로 유리질 내지 라필리 응회암이 속성 변질된 것으로 이 과정에서 SiO2와 알칼리 (Na, K) 성분들이 고갈되는 화학 성분상의 유동 양상이 인지된다. 벤토나이트는 주된 광물 성분인 스멕타이트 이외에 흔히 단백석 및 석영같은 규산 광물과 휼란다이트, 모데나이트 및 클리높틸로라이트간은 불석광물들을 수반한다. 스멕타이트는 대부분 몰노릴로나이트 유형이지만 최상부 층준의 현무암질원 벤토나이트와 비교하여 논트로나이트의 광물 화학, X-선회절 양상, 층간 화학 및 염화학적 특성 등이 논의되었다. 이 지역 벤토나이트의 형성과정은 (1) 화산쇄설물의 급속한 퇴적, (2) 비이상적으로 높은 매몰 온도(<8$0^{\circ}C$) 조건, (3) 규산 광물의침전에 의한 공극수 내외 H4SiO4의 제거, (4) 원암의 낮은 Si/al 함유비와 높은 Fe 함유도 등에 의해서 조장된 것으로 해석된다.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.616-621
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• 1990

The spectrophotometric methods for the determination of Nd, Pr, Sm, Eu, Ho, Er were developed, using the multicomponent method of absorption spectra cointerference. The absorption spectra of individual Nd, Pr, Sm, Eu, Ho, Er, mixture of Sm, Eu, Ho, Er in hydrochloric acid solutions were investigated, and also a band register which includes the molar absorptions for all trivalent Nd, Pr, Sm, Eu, Ho and Er absorption band maxima were measured. The spectrophotometric determination of Nd, Pr, Sm, Eu, Ho and Er were investigated using the analytically significant absorption bands at 444.2, 575.1, 401.7, 394.2, 416.6, and 379.7 nm, respectively.