• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.218-218
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• 2007

고체 전해질로서 $CsH_2PO_4$결정은 $230^{\circ}C$ 이상에서 전기전도도가 $10^{-2}\;{\Omega}^{-1}cm^{-1}$의 값에 도달하는 초양성자(Superprotonic) 상태로 상전이를 한다. 이러한 이유로 $CsH_2PO_4$ 결정은 $230^{\circ}C$ 부근에서 사용할 수 있는 연료전지로 개발되어왔다. 실용적인 면에서 단결정의 경우보다 다결정의 물성 및 응용 연구가 많았는데, 입자 크기에 따른 체계적인 연구는 잘 이루어지지 않았다. 본 발표에서는 $CsH_2PO_4$ 다결정을 합성하여 SEM 및 micro Raman spectra를 조사하였다. SEM의 결과 입자들의 평균 크기는 100 nm 이었으며, micro Raman spectra는 Bulk $CsH_2PO_4$의 spectra 와 큰 차이를 보이지 않았다. $PO_4$의 내부진동은 거의 같은 주파수대를 보여주나, $300\;cm^{-1}$이하의 저주파 수 영역에서는 광학적 포논의 픽이 잘 보이지 않았다. 그 원인이 micro Raman 장치의 측정 특성인지, 물리적 변화인지는 확실치 않다.

• Journal of the Korean Magnetic Resonance Society
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• 제19권1호
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• pp.29-35
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• 2015

The microscopic dynamics of $CsH_2PO_4$, with two distinct hydrogen bond lengths, are studied by static nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR. The proton dynamics of the two crystallographically inequivalent hydrogen sites were discussed in terms of the $^1H$ NMR and $^1H$ MAS NMR spectra. Although the hydrogen bonds have two inequivalent sites, H(1) and H(2), distinct proton dynamics for the two sites were not found. Further, the $^{133}Cs$ spectrum is more or less continuous near $T_{C1}$ (=153 K). Finally, the phase transition mechanism of $T_{C1}$ in $CsH_2PO_4$ is related to the ordering of protons.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제4권4호
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• pp.311-320
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• 2006

Removal characteristics of $H^{14}CO_3$ ion from IRN-150 mixed resin contaminated with $^{14}C$ radionuclide and a gasification behavior of $^{14}C$ radionuclide to $^{14}CO_2$ were investigated. The stripping solutions used for the removal of $^{14}C$ from spent resin were $NaNO_3,\;Na_3PO_4,\;NH_4H_2PO_4,\;H_3PO_4$. The influence of stripping solution concentration on the desorption characteristics of inactive $HCO_3$ ion into stripping solution from IRN-150 mixed resin and the gasification of this ion to $CO_2$ was analyzed. The gasification behavior to $CO_2$ by using NaOH, $HNO_3$, HCl was also compared to that of phosphate solution. Real spent resin stored in Wolsung nuclear power plant was used to evaluate the gasification characteristics of $^{14}C$ radionuclide to $^{14}CO_2$. Gamma radionuclides such as $^{137}Cs,\;^{60}Co$ in residual striping solutions after desorption experiment were analyzed.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.847-856
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• 2014

Spent resin waste containing a high concentration of $^{14}C$ radionuclide cannot be disposed of directly. A fundamental study on selective $^{14}C$ stripping, especially from the IRN-150 mixed bed resin, was carried out. In single ion-exchange equilibrium isotherm experiments, the ion adsorption capacity of the fresh resin for non-radioactive $HCO_3{^-}$ ion, as the chemical form of $^{14}C$, was evaluated as 11mg-C/g-resin. Adsorption affinity of anions to the resin was derived in order of $NO_3{^-}$ > $HCO_3{^-}{\geq}H_2PO_4{^-}$. Thus the competitive adsorption affinity of $NO_3{^-}$ ion in binary systems appeared far higher than that of $HCO_3{^-}$ or $H_2PO_4{^-}$, and the selective desorption of $HCO_3{^-}$ from the resin was very effective. On one hand, the affinity of $Co^{2+}$ and $Cs^+$ for the resin remained relatively higher than that of other cations in the same stripping solution. Desorption of $Cs^+$ was minimized when the summation of the metal ions in the spent resin and the other cations in solution was near saturation and the pH value was maintained above 4.5. Among the various solutions tested, from the view-point of the simple second waste process, $NH_4H_2PO_4$ solution was preferable for the stripping of $^{14}C$ from the spent resin.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.147-157
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• 2004

The production of $^{14}C$ occurs in the Moderator(MOD), Primary Heat Transport System (PHTS), Annulus Gas System(AGS) and Fuel in the CANDU reactor. Among the four systems, The MOD system is the largest contributor to $^{14}C$ production(approximately 94.8%). $^{14}C$ is distributed of $^{14}CO_2$, $H_2^{14}CO_3$, $H^{14}{CO_3}^-$ and $^{14}{CO_3}^{2-}$ species as a function of the pH of water. Of these species, $H_2^{14}CO_3$ and $H^{14}{CO_3}^-$ form are predominant because the pH of MOD system is ＞ 5. In this paper, adsorption-desorption characteristics of bicarbonate ion (${HCO_3}^-$) by IRN 150 resin was investigated. ${HCO_3}^-$ ion existed in neutral condition(app. pH 7)was reacted with ion exchange resin (IRN-150) and saturated with it. Then $NaNO_3$ and $Na_3PO_4$ solutions selected as extraction materials were used to make an investigation into feasibility of ${HCO_3}^-$ extraction from resin saturated with ${HCO_3}^-$. Desorption of $CO^{2+}$ and $Cs^+$ ion by $Na^+$ ion was not occurred, and desorption of ${HCO_3}^-$ ion by ${NO_3}^-$ and ${PO_4}^{3-}$ was occurred slowly. Also, the status of ion exchange which is used in Wolsong NPPs and generation of spent resin yearly were surveyed.

• Journal of Environmental Science International
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• 제22권6호
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• pp.705-715
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• 2013

The response of the freshwater microalga Chlorella vulgaris to mercuric ion ($Hg^{2+}$) stress was examined using chlorophyll a fluorescence image analysis and O-J-I-P analysis as a way to monitor the toxic effects of mercury on water ecosystems. The levels of photosynthetic pigments, such as chlorophyll a and b and carotenoids, decreased with increasing $Hg^{2+}$ concentration. The maximum photochemical efficiency of photosystem II(Fv/Fm) changed remarkably with increasing $Hg^{2+}$ concentration and treatment time. In particular, above $200{\mu}M\;Hg^{2+}$, considerable mercury toxicity was seen within 2 h. The chlorophyll a fluorescence transient O-J-I-P was also remarkably affected by $Hg^{2+}$; the fluorescence emission decreased considerably in steps J, I, and P with an increase in $Hg^{2+}$ concentration when treated for 4 h. Subsequently, the JIP-test parameters (Fm, Fv/Fo, RC/CS, TRo/CS, ETo/CS, ${\Phi}_{PO}$, ${\Psi}_O$ and ${\Phi}_{EO}$) decreased with increasing $Hg^{2+}$ concentration, while N, Sm, ABS/RC, DIo/RC and DIo/CS increased. Therefore, a useful biomarker for investigating mercury stress in water ecosystems, and the parameters Fm, ${\Phi}_{PO}$, ${\Psi}_O$, and RC/CS can be used to monitor the environmental stress in water ecosystems quantitatively.

• Journal of Applied Biological Chemistry
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• 제54권2호
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• pp.135-142
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• 2011

A feather-degrading bacterium Elizabethkingia meningoseptica CS2-1 was isolated from compost in a chicken farm. Cultured on a basal medium containing 2% chicken feather, the bacterium showed 729.7 ${\mu}mol/mL$ of amino acid. Optimal culture conditions for feather degradation by E. meningoseptica CS2-1 were $25^{\circ}C$, pH 7.5, and 180 rpm. The optimal pH and temperature for protease activity were 8.0 and $40^{\circ}C$, respectively. The composition of an optimal medium for amino acid production was 0.05% NH4Cl, 0.05% NaCl, 0.03% $K_2HPO_4$, 0.03% $KH_2PO_4$, 0.01% $MgCl_2{\cdot}6H_2O$, 0.1% urea, and 2% chicken feather. Characteristics of amino acids extracted from the optimal medium under the optimal culture conditions of E. meningoseptica CS2-1 were analyzed. The total amino acid content of strain CS2-1 was 1063 ${\mu}mol/mL$, which was 46% higher compared to the basal condition (729.7 ${\mu}mol/mL$). The essential amino acid content in the total amino acid was 315.9 ${\mu}mol/mL$, which was 44% higher than that of the basal condition. Major amino acids were proline (14%), aspartic acid (12%), glutamic acid (11%), serine (10%), alanine (10%), glycine (9%), and tyrosine (7%) by strain CS2-1. These results suggest that strain CS2-1 can be used as a potential microbial resource for the production of amino acid using chicken feathers.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제4권4호
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• pp.373-384
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• 2006

Spent ion-exchanged resin generated from various purification systems in CANDU reactor was contaminated with high activity of $^{14}C$ radionuclide. This paper describes the results of fundamental study to develop the applicable technology for the treatment of this spent resin. Based on the adsorption capacity of inactive $HCO_3$ ion and other anions on IRN-150 mixed resin, the removal characteristics of $HCO_3$ ion adsorbed on to IRN-150 by various stripping solutions were evaluated. Maximum adsorption amount of the $HCO_3$ ion onto IRN-150 raw resin was about 11 mg-C/g-resin which agrees with the theoretical adsorption amount of this resin. Adsorption affinity of various anions such as $CS,\;CO,\;Na\;NH_4$ was analyzed in single and multi-component systems. From the results of removal characteristics of the $HCO_3$ ion adsorbed on IRN-150 by various stripping solutions, $NH_4H_2PO_4$ stripping solution is more effective than $NaNO_3,\;Na_3PO_3$ solutions for the complete removal of $^{14}C$ radionuclide from the IRN-150 spent resin.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3197-3198
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• 2013

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제3권1호
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• pp.57-65
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• 2005

This study suggested a new method for the solidification of molten salt waste generated from the electro-metallurgical process in the spent fuel treatment. Using binary material system, sodium silicate and phosphoric acid, metal chlorides were converted into metal phosphate in the micro-reaction module formed by SiO$_{2} particles. The volatile element in the reaction module would little vaporized below 1100$^{circ}$C After the gel product was mixed with borosilicate glass powder and thermally treated at 1000$^{circ}$C, li exists as Li$_{3}$PO$_4$ separated from glass phase and, Cs and Sr would be incorporated into an amorphous phase from XRD analysis. In case of the addition of ZrCl$_{4}$ to the binary system, the gel products were transformed into NZP structure considered as an prospective ceramic waste form after heat-treatment above 700 $^{circ}$C. From these results, the gel-route pretreatment can be considered as an effective approach to the solidincation of molten salt waste by the confirmed process or waste form and this also would be an alternative method on the ANL method using zeolites in USA by the confirmation of its chemical durability as an future work.