• Title/Summary/Keyword: ceramic pellet

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The Effect of PVA-Al(III) Complex on Pore Formation and Grain Growth of $UO_2$ Sintered Pellet (II) (PVA-A(III) 착물이 $Uo_2$ 소결체의 기공형성과 결정립성장에 미치는 영향(II))

  • 이신영;김형수;노재성
    • Journal of the Korean Ceramic Society
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    • v.36 no.8
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    • pp.782-790
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    • 1999
  • The compressibility sinterability sintering behaviour and thermal stability of AlOOH added UO2 pellt and PVA-Al(III) complex added UO2 pellet were investigated respectively. Compared with characteristics of AlOOH added UO2 pellet the green density and the sintered density of PVA-Al(III) complex added UO2 pellet were lowered but the grain size and the pore size of that were more increased in accordance with higher compacting pressure. The AlOOH added UO2 pellet had the grain size of about 14${\mu}{\textrm}{m}$ with monomodal pore size distribution while the PVA-Al(III) complex added UO2 pellet had the grain size of about 42 ${\mu}{\textrm}{m}$ with bimodal pore size distribution. The PVA-A(III) complex added UO2 pellet had a similiar open porosity to the AlOOH added UO2 pellet and a lower resintered density change than the AlOOH added UO2 pellet.

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Effects of Koryo Hand Therapy on Menstrual Cramps and Dysmenorrhea in College Women Students (고려수지요법이 여대생의 생리통 및 월경곤란증에 미치는 효과)

  • Kim, Chung-Nam;Chang, Young-Sim
    • Research in Community and Public Health Nursing
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    • v.14 no.3
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    • pp.432-444
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    • 2003
  • Purpose: This study attempted to verify the effect of Koryo hand therapy on menstrual cramps and dysmenorrhea among college students. Method: This study performed the quasi-experimental design with nonequivalent control group and the pre and post-test design from August 28 to November 4, 2002. The subjects of this experimental study consisted of 64 college students in the nursing college of K University in D city and K college students in K city, who had more than 5.0 GRS score of menstrual cramps. Among them, 16 people belonged to the experimental group A by using Ceramic Seo Am moxa therapy, 16 to the experimental group B by using Seo Am pellet therapy, 16 to the experimental group C by using combination of Ceramic Seo Am moxa therapy and Seo Am pellet therapy and 16 to the control group. Three different kinds of methods were used three times per week for $5{\sim}6$ weeks(a total of $15{\sim}18$ times) interventions were completed. For the experimental group, A Ceramic Seo Am moxa therapy was given for 40 minutes per each treatment; for the experimental group, B Seo Am pellet therapy was given for 4 hours: for the experimental group, C combination of Ceramic Seo Am moxa therapy and Seo Am pellet therapy was given. To measure menstrual cramps, the graphic rating scale (GRS) was used and to measure dysmenorrheal, a dysmenorrhea scale (15 contents) was used, which was modified from Han &Hur's scale (13 contents). Cronbach's was 0.78 in the pre-test, 0.83 in the first post-test, 0.89 in the following post-test. Data were analyzed by one-way ANOVA, 2 test, repeated measures ANOVA, time contrast test and Sheffe test with the SPSS/Win 11.0 program. Results: ? The first hypothesis, 'Among the experimental group A by using Ceramic Seo Am moxa therapy, the experimental group B by using Seo Am pellet therapy and the experimental group C by using combination of Ceramic Seo Am moxa therapy and Seo Am pellet therapy will have different graphic rating scores of menstrual cramps', was supported (F=6.77, p=0.000, Interaction: p=0.000). ? The second hypothesis, 'Among the experimental group A by using Ceramic Seo Am moxa therapy, the experimental group B by using Seo Am pellet therapy, the experimental group C by using combination of Ceramic Seo Am moxa therapy and Seo Am pellet therapy and the control group will have a significantly different level of dysmenorrhea', was supported (F=6.88, p=0.000, Interaction: p=0.000). From the above results, it can be an effective nursing intervention to give Koryo hand therapy to college students who have menstrual cramps and dysmenorrhea. Conclusion: These findings indicate that Koryo hand therapy could be applied to improve the quality of life and to prevent drug misuse among college students who are physically, mentally and psychologically suffering from menstrual cramps and dysmenorrhea. Furthermore, Koryo hand therapy could be developed as an effective Korean alternative and complementary care in the future. and it could also provide a guideline to apply Koryo hand therapy to other pain and difficulties.

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Effects of Additives on the Characteristics and Microstructure of $UO_2$ Pellet ($UO_2$ 소결체의 특성 및 미세구조에 미치는 첨가제의 영향)

  • 유호식;이신영;이승재;강권호;김형수
    • Journal of the Korean Ceramic Society
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    • v.37 no.7
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    • pp.660-664
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    • 2000
  • Effect of various kinds of additive such as AlOOH, Al(OH)3, Al2Si2O5(OH)4, Nb2O5, TiO2 and MgO on the properties and microstructures of UO2 pellet has been examined. All the tested dopants had played a role to reduce sintered density and open porosity. It was revealed that the addition of TiO2 made pellet more stable thermally. UO2 pellet doped with 0.2wt% TiO2 was swelled rather than densified after annealing for 24 hrs at 1$700^{\circ}C$. It was attributed to large pore with spherical shape. Titinia and silicon coexisted with Al element were more effective to increase grain size than other additives. It could be also revealed that the formation of liquid phase was the main cause of grain growth.

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Effect of UO2+x Powders Produced at Different Oxidation Temperatures on the Properties of Pellet

  • Yoo, Ho-Sik;Lee, Seung-Jae;Kim, Jae-Ik;Song, Kun-Woo
    • Journal of the Korean Ceramic Society
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    • v.40 no.5
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    • pp.410-414
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    • 2003
  • Characteristics of $UO_{2+x}$ powders oxidized at different temperatures were examined. Pellets were fabricated by adding these oxidation powders and their properties were also investigated. Particle size of the $UO_{2+x}$ powders decreased with increasing oxidation temperature while surface area increased. Only the powders oxidized at 35$0^{\circ}C$ enhanced the strength of green pellet. However, 35$0^{\circ}C$ oxidized powders added pellet had many surface defects. The difference of shrinkage rate between the oxidized and UO$_2$ powders was thought to be the cause of them.

The Effect of PVA-Al(III) Complex on the Pore Formation and Grain Growth of UO$_2$ Sintered Pellet (PVA-Al(III) 착물이 UO$_2$ 소결체의 기공형성과 결정립성장에 미치는 영향(I))

  • 이신영;김형수;노재성
    • Journal of the Korean Ceramic Society
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    • v.35 no.8
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    • pp.783-790
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    • 1998
  • The characterization of the complexation reaction of PVA and Al(III) ion at different pH and the sint-ering behaviour of UO2 containing the PVA-Al(III) complexes were investigated. Compared with pure PVA powder the complexed PVA-Al(III) powder had compacter shape and lower decomposition temperature The major phase of PVA-Al(III) complex decomposed at 90$0^{\circ}C$ was $\alpha$-Al2O3 The PVA-Al(III) complex formed at pH 9 had the lowest relative viscosity the highest Al content of 36% and the smallest particle size of 19${\mu}{\textrm}{m}$ While the pure UO2 pellet appeared with bimodal one. The grain size of the pure UO2 pellet was 7${\mu}{\textrm}{m}$ but that of the PVA-Al(III) complex added UO2 pellet was increased up to 36${\mu}{\textrm}{m}$ The largest grain size was ob-tained when the PVA-Al(III) complex formed at pH9 was added and the PVA-Al(III) complex formed at pH 11 had the greatest effect on increasing pore size.

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Effect of the Addition of Aluminium Distearate on Manufacturing of $UO_2$ Nuclear Fuel (Aluminium Distearate 첨가가 $UO_2$ 핵연료 제조에 미치는 영향)

  • 박지연;정충환;김영석
    • Journal of the Korean Ceramic Society
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    • v.29 no.8
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    • pp.609-616
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    • 1992
  • This study has been investigated on the milling of Aluminium Distearate (ADS) powder and characteristics of the ADS-doped UO2 pellets. As-received ADS powder of the agglomerated particles has not shown any milling effect because of heat generated during planetary milling. But the use of coolant to effectively remove heat generated during milling has been found an effective way in breaking up the agglomerates of ADS powder. The green density of the UO2 pellet decreases with the amount of ADS powder doped. Therefore, in order to get the sintered density of 95% pellet decreases with the amount of ADS powder doped. Therefore, in order to get the sintered density of 95% theoretical density, the 200 ppm ADS-doped UO2 pellet has to be pressed under higher compacting pressure of 3500~4000 kgf/$\textrm{cm}^2$ compared with the ADS-undoped UO2 pellet pressed under around 3000 kgf/$\textrm{cm}^2$. The ADS-dpoed UO2 pellet with even relatively low sintered density of 10.27 g/㎤ exhibits open porosity of 1% while open porosity of the ADS-undoped UO2 pellet is reduced to around 1% only after its sintered density increases to 10.43g/㎤. It is, therefore, concluded that doping of ADS powder significantly contributes to the decrease in open porosity of the UO2 pellet. The dilatometry of the ADS doped UO2 pellet shows the sintering rate curve with the bimodal mode, which could be attributed to a phase reaction between UO2 and ADS. The X-ray diffraction analysis indicates that there occurs not any new phase formed but the shift of the peaks. It would be expected that a phase reaction resulting in solid solution would happen in the temperature range of 130$0^{\circ}C$ to 150$0^{\circ}C$ between UO2 and ADS.

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Development status of microcell UO2 pellet for accident-tolerant fuel

  • Kim, Dong-Joo;Kim, Keon Sik;Kim, Dong Seok;Oh, Jang Soo;Kim, Jong Hun;Yang, Jae Ho;Koo, Yang-Hyun
    • Nuclear Engineering and Technology
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    • v.50 no.2
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    • pp.253-258
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    • 2018
  • A microcell $UO_2$ pellet, as an accident-tolerant fuel pellet, is being developed to enhance the accident tolerance of nuclear fuels under accident conditions as well as the fuel performance under normal operation conditions. Improved capture-ability for highly radioactive and corrosive fission product (Cs and I) is the distinct feature of a ceramic microcell $UO_2$ pellet, and the enhanced pellet thermal conductivity is that of a metallic microcell $UO_2$ pellet. The fuel temperature can be effectively decreased by enhanced thermal conductivity. In this study, the material concepts of metallic and ceramic microcell $UO_2$ pellets were designed, and the fabrication process of microcell $UO_2$ pellets embodying the designed concept was developed. We successfully implemented the microcell $UO_2$ pellets and produced microcell $UO_2$ pellets. In addition, an assessment of the out-of-pile properties of a microcell $UO_2$ pellet was performed, and the in-reactor performance and behavior of the developed microcell pellets were evaluated through a Halden irradiation test. According to the expectations, the excellent performance of the microcell $UO_2$ pellets was confirmed by the online measurement data of the Halden irradiation test.

Design of the Dry Powder Device and Slitting Machine Device (탈피복 기계 장치와 건식 분말화 장치 설계)

  • 정재후;윤지섭;김영환;이종열;홍동희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.630-633
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    • 1997
  • Spent fuel decladding device and dry voloxidizer is to separate the spent pellet from spent fuel rod cut by 250mm and to convert the spent pellet into powder form for reuse and/or disposal of the spent fuel. There are two methods in decladding and voloxidation of spent fuel, that is, wet method with chemical material and dry method with mechanical device. In this study, to examine the fuel rod decladding process and the pellet voloxidation process, the devices for the spent fuel decladding and the pellet voloxidation with dry method are developed. The decladding machine is designed to separate pellets from fuel rod by slitting device. And, the voloxidizer is designed to convert the spent pellet which is ceramic form into powder form by oxidation using the multi step mesh, vibrator, and air in the high temperature environment. The result of this study, such as operation condition et., will be utilized in the design of the machine for demonstration.

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Iron Mixed Ceramic Pellet for Arsenic Removal from Groundwater

  • Shafiquzzam, Md.;Hasan, Md. Mahmudul;Nakajima, Jun
    • Environmental Engineering Research
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    • v.18 no.3
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    • pp.163-168
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    • 2013
  • In this study, an innovative media, iron mixed ceramic pellet (IMCP) has been developed for arsenic (As) removal from groundwater. A porous, solid-phase IMCP (2-3 mm) was manufactured by combining clay soil, rice bran, and Fe(0) powder at $600^{\circ}C$. Both the As(III) and As(V) adsorption characteristics of IMCP were studied in several batch experiments. Structural analysis of the IMCP was conducted using X-ray absorption fine structure (XAFS) analysis to understand the mechanism of As removal. The adsorption of As was found to be dependent on pH, and exhibited strong adsorption of both As(III) and As(V) at pH 5-7. The adsorption process was described to follow a pseudo-second-order reaction, and the adsorption rate of As(V) was greater than that of As(III). The adsorption data were fit well with both Freundlich and Langmuir isotherm models. The maximum adsorption capacities of As(III) and As(V) from the Langmuir isotherm were found to be 4.0 and 4.5 mg/g, respectively. Phosphorus in the water had an adverse effect on both As(III) and As(V) adsorption. Scanning electron microscopy results revealed that iron(III) oxides/hydroxides are aggregated on the surface of IMCP. XAFS analysis showed a partial oxidation of As(III) and adsorption of As(V) onto the iron oxide in the IMCP.

Microstructural Changes of AlOOH Doped $UO_2$ Pellet during the Annealing Process

  • Hosik Yoo;Lee, Shinyoung;Lee, Seungjae;Kwenho Kang;Kim, Hyoungsu
    • The Korean Journal of Ceramics
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    • v.6 no.3
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    • pp.209-213
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    • 2000
  • Microstructural changes of AlOOH doped UO$_2$pellet after annealing up to 216h have been observed and they were compared with those of the standard pellet. Grain and pore size of UO$_2$pellet increased with the addition of AlOOH and its effect was still validated during annealing. Densification rate was reduced by the addition of AlOOH and it was attributed to coarsened pores with spherical shape. Grain and pore growth was stopped and density increase was the least after 144h of annealing. The variation of pore size resulting from annealing has a linear relationship with that of grain size.

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