• 한국세라믹학회지
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• 제41권8호
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• pp.588-592
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• 2004

Dynamic Milling (DM) 방법에 의한 $UO_2$ 분말의 특성 변화가 밀도에 미치는 영향을 조사하였다 분쇄시간(0∼8시간)의 증가에 따라 분말입자의 크기는 감소하며 둥근 형태를 지녔으며, 비표면적과 O/U 비는 증가하였다. 이러한 특성 변화에 의해 성형밀도는 증가한 반면에, 소결밀도는 감소하는 경향을 보였다. 소결밀도의 감소는 분말 분쇄과정에서 야기된 $UO_2$ 분말의 O/U 비의 증가가 주된 영향을 미친 것으로 사료된다.

• 한국재료학회지
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• 제3권3호
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• pp.245-252
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• 1993

순수 $UO_2$에 첨가량 변화 및 ball-milling 시간에 따른 (U, Ce)$O_2$ 분말의 특성과 각 조건별로 제조된 분말을 압분 및 소결하여 (U, Ce)$O_2$ 분말 특성에 따른 소결성을 비교 조사하였다. 실험 결과로 부터 ball-milling시간이 길어짐에 따라 입자들은 미세화되고, Ce$O_2$ 함량이 증가할수록 압분, 소결밀도는 저하 하였으며, $CeO_2$는 소결성을 저하시키는 산화물임을 확인하였다. 10wt%,$CeO_2$ 가 첨가된 (U, Ce)$O_2$ 분말의 경우, ball-milling 4시간 수행한 분말의 소결체가 기공의 수도 적고, 구형에 가까왔으며, 소결밀도가 가장 높았다. 이는 4시간 ball-milling한 (U, Ce)$O_2$분말이 비표면적이 크로 그의 packing ratio가 적절하였기 때문이다.

• 한국환경과학회지
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• 제12권12호
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• pp.1321-1327
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• 2003

Two different kinds of cases, with and without addition of noncrystalline silica to the Hadong kaolin were studied to obtain useful information on the synthesis of zeolite. The research was carried out to investigate the formation area and the crystalized degree of zeolite according to a synthetic time, the water content of raw material mixture, KOH concentration, and stirring intensity. In the case of without addition of noncrystalline silica to the Hadong kaolin and the low concentration range of KOH, the structure of the kaolin was not changed. However, when the mole ratio of K2O/SiO$_2$ in natural kaolin was increased, Linde-L zeolite and unknown structure of kaolins, U-1 and U-2 were produced. While in the high concentration range of KOH, the unknown structure of kaolins, U-6 and U-2, were produced and the production rate of U-6 was increased with the increased of K2O/SiO$_2$ mole ratio. In the case of with addition of noncrystalline silica to the Hadong kaolin and treatment with KOH hydrothermal processing, ZSM-5, ZSM-35, and Linde-L zeolites and the mixture of unknown structure of zeolites, U-1, U-2, U-3, and U-4, were obtained. Both cases demonstrated that the synthesis of zeolite from the Hadong kaolin was highly influenced by KOH concentration of raw material mixture.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.419-425
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• 2024

The purpose of this study is to improve the concentration of U(VI) in carbonate solution reasonably, which to improve the application potential of the alkaline reprocessing processes. The dissolution behavior of U₃O₈ in carbonate peroxide solutions was investigated under different conditions, including pH, carbonate concentration, and solid-liquid ratio. The results showed that the dissolution rate of U₃O₈ increased with the increase of pH from 8 to 11 in the mixed carbonate solution containing 0.5 mol/L H₂O₂. The role of carbonate ions in the dissolution of U₃O₈ was further elucidated by observing the dissolution of UO₄⋅4H₂O in carbonate solutions. Furthermore, the concentration of U(VI) in 3 mol/L Na₂CO₃ solution was successfully increased to 350 g/L under ultrasonic-assisted conditions at 60 ℃ and a solid-liquid ratio at 1/2 g/mL. Meanwhile, it is suggested that increasing the concentration of carbonate ions can improve the stability of the dissolved solution containing uranyl peroxycarbonate complex.

• 지질공학
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• 제32권2호
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• pp.295-310
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• 2022

월악산-속리산 화강암은 SiO₂와 알카리(Na₂O+K₂O) 함량이 높고 CaO와 P₂O₅는 결핍된 원소 특성을 보인다. 또한 화강암의 알루미나 포화지수는 1.3 이상으로 과알루미나질 특성을 보인다. U과 Th의 평균 함량은 각각 8.3과 39.3 ppm으로서 국내 중생대 화강암 중에서 가장 높은 방사성 원소 함량을 보이며, 화강암의 세계 평균보다 약 2배 정도로 높다. 이러한 높은 방사성 원소 함량 특성은 화강암의 고분화 특성과 대륙지각 기원의 암석 성인에 기인한다. U 또는 Th을 함유하는 방사성 광물은 저어콘, 토라이트, 모나자이트, 제노타임, 퍼구소나이트, 우라니나이트 등이다. 화강암의 Th/U 비 평균값이 5.4로서 지각 평균값과 유사하다는 것은 방사성 원소의 화강암 내 분포가 지각 기원 물질의 마그마 작용에 조절되었음을 의미한다. U과 Th에 대한 Zr, Y, HREE 간의 상관관계로 보아, 방사성 원소는 저어콘이나 모나자이트보다는 주로 제노타임에 포함되어 산출되는 것으로 해석된다.

• 산업경영시스템학회지
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• 제20권43호
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• pp.205-209
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• 1997

One objective of the u control chart is to detect changes of mean nonconformities per unit occurred owing to various causes. This paper shows the detection probability using the Poisson distribution for various parameters, that is, subsample size n, mean nonconformities per unit $u_o$, and $u_o's$ change ratio k. We find that (1) as $u_o$ increases the smaller n is required for the same detection probability and the same change ratio; (2) as k gets away from 1 the smaller n is required; (3) the bigger n is required for the bigger detection probability. Several tables are given from our findings and are hoped to be used as guidelines for u chart users.

• 한방재활의학과학회지
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• 제18권2호
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• pp.97-109
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• 2008

Objectives : Effects of Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) on intellectual development and learning ability were investigated growth and intellectual impairment rat with insufficient nutrition diet. Methods : We divided male Sprague-Dawley rats into 4 groups(A, B, C, D). They were normal group(A), growth deficiency rat with insufficient nutrition diet group(B), growth deficiency rat with 0.1% Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) group(C) and growth deficiency rat with 0.2% Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) group(D). They were administered for 5 weeks. We measured body weight, serum growth hormone, insulin-like growth factor and thyroid stimulating hormone, RBC, concentration of Hb and PCV ratio, total WBC and its composition, the values of plasma glutamic oxaloacetic transaminase(GOT) and glutamic pyruvic transaminase(GPT) activities and morris water maze test in escape distance, escape time and escape speed. Results : 1. Body weight showed a tendency to increase in the Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) groups and 0.2% Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) group showed significantly different than control groups. 2. Serum growth hormone, insulin-like growth factor and thyroid stimulating hormone showed a tendency to increase in Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) groups, however these values showed no significantly different. 3. About the counts of RBC, 0.1% and 0.2% Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) groups showed significantly different than control groups. Concentration of Hb was higher than control group in Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) groups. And 0.2% Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) group showed significantly different than control groups in PCV ratio. 4. The counts of total WBC and its composition showed no significantly different in all treatment groups. 5. The values of plasma glutamic oxaloacetic transaminase(GOT) and glutamic pyruvic transaminase(GPT) activities showed no significantly different in all treatment groups. 6. In the morris water maze test, in escape distance and escape speed, Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) groups showed no significantly different than control group. But Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) groups showed the increasing tendency. Conclusions : So Kyungohkgo($Qi{\acute{o}}ng\;y{\grave{u}}\;g{\grave{a}}o$) have an effect of promoting growth of rats and might be effect to treat various kinds of growth delay in children.

• E2M - 전기 전자와 첨단 소재
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• 제7권4호
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• pp.281-288
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• 1994

According to spread volume of B(BiPbCuO) layer, composition ratio and each stage of sintering process, we studied stability of high Tc superconductor phase and generation and growth movement of superconducting phase. The dual layer composed of SrCaCuO and BiPbCuO compound were prepared to develop the Bi-2223 superconductor[108K] through interaction and diffusion during sintering process. The dual layer samples were sintered at 830.deg. C for 0-210 hours. From the result, the optimum conditions were : spread volume(A:B=1:0.6), sintering time(210h) and composition ratio(A:S $r_{2}$C $a_{2}$C $u_{2}$- $O_{x}$, B:B $i_{1.9}$P $b_{0.5}$C $u_{3}$ $O_{y}$) at 830.deg. C.. C.C.C.

• Nuclear Engineering and Technology
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• 제31권3호
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• pp.335-343
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• 1999

The effects of N $b_2$ $O_{5}$ and oxygen potential on the densification and grain growth of U $O_2$ fuel have been investigated.0.3 wt% N $b_2$ $O_{5}$ -doped U $O_2$fuel pellets were sintered at 1$700^{\circ}C$ for 4 hours in sintering atmospheres which have various ratios of $H_2O$ to $H_2$ gas. Compared with those of undoped U $O_2$ pellets, the sintered density and grain size of the 0.3 wt% N $b_2$ $O_{5}$ -doped U $O_2$ pellet increase under the $H_2O$/ $H_2$ gas ratio of 5.0$\times$10$^{-3}$ to 1.0$\times$10$^{-2}$ and under the $H_2O$/ $H_2$gas ratio of 5.0$\times$10$^{-3}$ to $1.5\times$10$^{-2}$ , respectively. The sintering of U $O_2$fuel pellets containing 0.1 wt% to 0.5 wt% N $b_2$ $O_{5}$ was carried out at 168$0^{\circ}C$ for 4 hours. The enhancing effect of N $b_2$ $O_{5}$ on the sintered density and grain size becomes larger as the N $b_2$ $O_{5}$ content increases. The solubility limit of N $b_2$ $O_{5}$ in U $O_{2}$ seems to be between 0.3 wt% and 0.5 wt%, and beyond the solubility limit the second phase whose composition corresponds near to N $b_2$U $O_{6}$ is precipitated on grain boundary. The enhancement of densification and grain growth in U $O_2$ is attributed to the increased concentration of a uranium vacancy which is formed by the interstitial N $b^{4+}$ ion in the U $O_2$ lattice.

• 공업화학
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• 제9권2호
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• pp.278-285
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• 1998

배출가스중의 $SO_2$ 제거를 위하여 다양한 금속산화물로 구성된 천연망간광석, 철광석, $CuO/{\gamma}-A1_2O_3$ 등을 흡착제로 사용하여 고정층반응기에서 흡착용량실험을 하였다. 또한 흡착제중 흡착용량이 떨어지는 철광석을 제외한 두 가지 흡착제를 이용하여 유동층반응기에서 유속, 온도, 입자크기 등의 조업조건에 따른 $SO_2$ 흡착실험을 수행하였다. 모든 흡착제에서 온도가 증가할수록 흡착량이 증가하는 화학흡착반응을 보였고 유동층반응기에서 $U_o/U_{mf}$ 및 $U_o-U_{mf}$와 같은 유속조건에 따라 입자 크기에 따른 흡착량의 변화가 다르게 나타났으며 유동층반응기 성능식으로부터 반응속도상수를 얻었다. 이 실험을 통하여 천연망간광석이 유동층반응기에서 $SO_2$ 흡착제로의 사용가능성을 확인할 수 있었다.