• Nuclear Engineering and Technology
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• 제26권2호
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• pp.190-196
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• 1994

AUC 공정으로 변환된 $UO_2$ 분말의 ball-milling 효과를 관찰하기 위하여 ball-milling 시간에 따른 소결성을 연구하였다. Ball-milling된 분말은 구형화 형태를 보이며, 그의 입자 크기 분포는 bimodal 양상을 나타냈다. 분말크기 분포가 bimodal인 경우, 그의 packing ratio가 monomodal gaussian 분포에 비해 높다. Ball-milling된 분말의 소결밀도 증가는 packing ratio에 의한 영향이 컸으며, ball-milling 시간이 길어질수록 packing ratio는 증가 하였다. AUC 공정으로 변환된 $UO_2$ 분말은 ball-milling을 함으로써, 그의 소결성이 향상됨을 확인하였다.

• Nuclear Engineering and Technology
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• 제31권6호
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• pp.608-617
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• 1999

The powder mixture which has a bimodal size distribution, with a large mode corresponding to AUC-UO$_2$ powder and a small one corresponding to ADU-UO$_2$ powder, was prepared, pressed into compacts, and sintered at 1680t for 4 hours in hydrogen gas. The compact density of the powder mixture increases with increasing ADU-UO$_2$content within a content of 20 wt %, since small ADU-UO$_2$ particles can fill interstices between large AUC-UO$_2$particles. The UO$_2$ pellet made using the powder mixture has a lower open porosity than that made using AUC-UO$_2$ powder alone. The mechanism for the formation of a flake-like pore is proposed, and the decrease in open porosity may be ascribed to the decrease in the number of flake-like pores.

• Nuclear Engineering and Technology
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• 제34권1호
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• pp.60-67
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• 2002

The effects of ball-milling time(0 ~4 hrs) have been investigated on the change of powder characteristics, compaction behavior (compaction pressure range : 200 ~400MPa) and sinterability (1700'c in Ha atmosphere) of two different UO$_2$ powders (ex-ADU and ex-AUC) prepared by the wet process. It is observed that, while the ex-ADU UO$_2$ was little affected, the ex-AUC UO$_2$ was largely affected by the ball-milling treatment. This may be attributed to the characteristics of particle size formed during the preparation step, i.e.., the former has a small average size of about 1.0${\mu}{\textrm}{m}$, while the latter has a relatively large average size of about 301n. It appeared that the effective size reduction by ball-milling treatment is limited to the particle size larger than l${\mu}{\textrm}{m}$, and to the extent of maximum decrease in size of about 0.5tn. In the case of ex-AUC UO$_2$, it is observed that the particle size decreased with ball-milling time and green density and sintered density of the pellets prepared from ball-milled powder increased compared with those of pellets prepared from the as-received powder under the same conditions. This may be attributed mainly to the fine particles formed during the ball-milling treatment.

• 한국세라믹학회지
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• 제33권3호
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• pp.332-338
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• 1996

This study was investigated on the recycle feasibility of the waste AC(Ammonium Carbonate) solution produ-ced in a commercial AUC(Ammonium Uranyl Carbonate) conversion plant. AUC particles were produced with the AC solution which was prepared with AC solid-agent instead of ammonia and carbon-dioxide gases. As the results particles of monoclinic shapes has been obtained regardless of the pH change if the carbonate concentration is sufficient in the mother liquore. Also a lot of twinned or aggregated particles were formed in case of the increase of pH in the reaction system but not affected in the change of temperature. Consequen-tly the characteristics of the particles which converted for AUC were produced withAC solution to UO2, particles specific surface area shape sintered density and others were similar to that of the particles which were produced with gases only when the pellets are fabricated in the nuclear fuel manufacturing process So the waste AC solution which is produced in the commercial AUC conversion plant is possible to recycle.

• 한국세라믹학회지
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• 제30권4호
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• pp.279-288
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• 1993

A study on calcination and reduction of AUC(ammonium uranyl carbonate, (NH4)4UO2(CO3)3) has been carried out by using TG-DTA in N2, air and H2 atmospheres, respectively. Phases of various intermediate obtained during thermal analysis of AUC in different atmospheres were confirmed by XRD. Powder characteristics of each intermediate were investigated by measuring particle size and specific surface area, and also observed by SEM. As a results, regardless of applied atmosphere AUC was calcined into amorphous UO3, which was converted to $\alpha$-U3O8 Via $\alpha$-UO3 in both H2 and N2 atmosphere, but directly into $\alpha$-UO3 in air atmosphere. Further reduction of U3O8 was only detectable in hydrogen atmosphere. During calcination and reduction, average particle size was reduced to less than 30% of original value without morphology change. Specific surface area was dramatically increased with release of NH3, CO2 and H2O from AUC powder and reached maximum value around 25$0^{\circ}C$, and then gradually decreased with the increase of temperature due to sintering effect of uranium oxides such as UO3 and U3O8. It was also found that the change of average crystallite size and pore size were closely related to the changes of specific surface area of uranium oxides.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 추계학술발표회요약집
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• pp.270-270
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• 1998

• 한국세라믹학회지
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• 제33권6호
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• pp.631-636
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• 1996

The powder characteristics of UO2 via AUC prepared by precipitation from a UN with AC soiution produced from nuclear fuel powder conversion plant and that of the existing facility were compared. Mean particle size of AUC powder was decreased and agglomerates were much occured in case of using the AC solution that that of the gases but other properties such as particle size distribution and shape of particle are thought to be similarly. In compaction of UO2 powder the breaking pressur of agglomerated UO2 powder and the sintered density of final UO2 pellet from AC solution were measured 1.45$\times$108 N/m2 and 10.52 g/cc, These values could be used in nuclear fuel powder fabrication process.

• Journal of Nutrition and Health
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• 제49권2호
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• pp.80-87
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• 2016

본 연구에서는 건강한 여대생 10명을 대상으로 하여 오리육에 농도를 달리한 울금을 첨가하여 섭취한 후 30분, 60분, 120분, 180분 후 혈액을 채취하여 울금 농도에 따른 혈중 지질농도의 변화를 살펴보았다. 연구결과는 다음과 같다. 1) 조사대상자는 병적 질환이 없고 신체조건이 한국인 기준에 해당되는 여대생 10명을 대상으로 하여 연구를 시행하였으며 대상자는 $159.6{\pm}2.6cm$, $51.3{\pm}3.5kg$이었으며, BMI는 $20.1{\pm}1.0$으로 정상 범위에 해당하였다. 공복시 혈당과 지질농도, GGT, GPT, GOT, CRP, 헤모글로빈 농도는 모두 정상 수준이었다. 2) 식후 혈중 포도당의 공복 시 혈당에 비해 증가된 ${\Delta}-AUC$값에서 유의적인 차이가 없었다. 3) 식후 혈중 총콜레스테롤은 울금 0.2%, 0.4% 첨가하였을 때 공복 시에 비한 ${\Delta}-AUC$값에서 대조군에 비해 유의적으로 낮았다. 4) 혈중 중성지방의 농도는 식후 90분 까지 0.4% 첨가군에서만 대조군에 비해 유의적으로 낮았다. 5) 식후 LDL의 공복 시에 비한 ${\Delta}-AUC$값은 울금 0.2%, 0.4% 첨가하였을 때 대조군에 비해 유의적으로 낮았다. 6) 식후 HDL의 공복 시에 비한 ${\Delta}-AUC$값은 울금 0.2%, 0.4% 첨가하였을 때 대조군에 비해 유의적으로 높았다. 본 연구는 혈중 지질상태가 정상인 여대생을 대상으로한 인체실험으로 0.2% 이상의 울금 첨가가 고지방식인 훈제오리육가공품의 섭취 시 혈중 지질농도에 영향을 미치고 있음을 밝힌 연구로 그 의미가 있다 할 것이다. 그러나 이의 기전을 보다 명확히 제시할 수 있는 다양한 조건에서의 추후 연구가 필요하다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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• pp.171-176
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• 1997

UO$_2$-Gd$_2$O$_3$fuel has been sintered to study the effect of powder property and sintering atmospheres on densification and microstructure. Three types of powders have been used; AUC-UO$_2$ powder and ADU-UO$_2$ powder were mixed with Gd$_2$O$_3$ Powder, and co-milled AUC-UO$_2$ and Gd$_2$O$_3$ powder. UO$_2$-(2, 5, 10)wt% Gd$_2$O$_3$pellets have been sintered at 168$0^{\circ}C$ for 4 hours in the mixture of H$_2$ and $CO_2$ gases, of which oxygen potential has been controlled by the ratio of $CO_2$ to H$_2$ gas. Densities of UO$_2$-Gd$_2$O$_3$ fuel pellets are quite dependent on powder types, and UO$_2$-Gd$_2$O$_3$ fuel using co-milled UO$_2$ powder yields the highest density. A long range homogeneity of Gd is determined by powder mixing. As the oxygen potential of sintered atmosphere increases, the sintered densities of UO$_2$-Gd$_2$O$_3$ pellets decrease but grain size increases. In addition, (U, Gd)O$_2$ solid solution becomes more homogeneous. The UO$_2$-Gd$_2$O$_3$fuel having adequate density and homogeneous microstructure can be fabricated by co-milling powder and by high oxygen potential.

• 공업화학
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• 제7권6호
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• pp.1164-1173
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• 1996

현재 국내에서 가동중인 원자력발전소 공급용 핵연료 분말제조 공정에서 발생되는 폐액의 물성과 처리방법에 대한 연구가 수행되었다. 중수로형과 경수로형 발생 폐액에 함유된 우라늄을 회수/처리하기 위하여, 공히 폐액 속의 탄산이온의 제거가 필수적이다. 중수로형은 ADU 형태로 경수로형의 경우 $UO_4$ 화합물 형태로 처리하는 것이, 최종 폐액의 우라늄 농도를 최소화할 수 있었다. 처리후 폐액의 우라늄 농도는 중수로형 폐액의 경우, 폐액을 가열하여 ADU를 제조한 후 여액에 lime을 처리하는 방법으로 1ppm까지, 경수로형 폐액의 경우 $UO_4{\cdot}2NH_4F$형태로 우라늄을 침전시킬 경우 0.8ppm까지 여액중의 우라늄 농도를 낮출 수 있었다. 최적 처리조건은 중수로형 폐액의 경우 $101^{\circ}C$까지 단순 가열방법이, 경수로형 폐액의 경우 가열한 후 $60^{\circ}C$에서 암모니아로 pH를 9.5로 조절한 후 과산화수소 용액을 첨가하여 1시간 반응시키는 경우로 나타났다. 폐액으로부터 회수된 우라늄 화합물은, 중수로형 폐액인 경우 pH가 낮을수록 회수된 ADU 입자의 크기가 증가하였으며, 경수로형 폐액인 경우 회수된 uranium peroxide 화합물을 공기분위기에서 열분해시킨 결과 기존의 AUC 분말이 열분해되어 나타내는 특성과 동일한 특성을 보임에 따라 핵연료분말 제조공정으로 recycle이 가능한 것으로 판단되었다.