• 전기화학회지
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• 제8권4호
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• pp.162-167
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• 2005

본 연구는 Pechini법을 이용하여 Ca과 Sr이 도핑된 $LaCrO_3$계의 $La_{0.6}Ca_{0.41}CrO_3$ (LCC41), $La_{0.8}Sr_{0.05}Ca_{0.15}CrO_3$, (LSCC), $La_{0.75}Ca_{0.27}CrO_3$ (LCC27) 분말들을 제조하여, 분말의 소결 특성 및 코팅층의 특성을 조사하였다. 제조된 LCC41, LSCC, LCC27 분말은 각각 0.6, 0.9, $1.5{\mu}m$의 평균 입자크기를 가졌으며, LCC41의 경우 $1400^{\circ}C$에서 98% 이상의 소결 밀도를 나타내었다. 연료극 지지체상의 LSCC 코팅은 LCC41층에 있는 Ca의 이동을 어느 정도 억제하는 역할을 하는 것으로 나타났다. 대기 용사 코팅된 LCC27은 치밀한 코팅막을 형성하였으며, 이 코팅층 위에 LCC41을 습식 코팅할 경우 더욱 치밀하고 높은 전기전도도를 갖는 코팅막을 얻을 수 있었다. 용사코팅된 LCC27, 습식 코팅된 LCC41는 높은 전기전도도를 나타내었으나, LSCC의 경우 낮은 소결성으로 인해 전기전도도가 작게 나타났다.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1210-1217
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• 2021

The analysis of ⁴¹Ca in concrete generated from the nuclear facilities decommissioning is critical for ensuring the safe management of radioactive waste. An analytical method for the determination of ⁴¹Ca in concrete is described. ⁴¹Ca is a neutron-activated long radionuclide, and hence, for accurate analysis, it is necessary to completely extract Ca from the concrete sample where it exists as the predominant element. The decomposition methods employed were the acid leaching, microwave digestion, and alkali fusion. A comparison of the results indicated that the alkali fusion is the most suitable way for the separation of Ca from the concrete sample. Several processes of hydroxide and carbonate precipitation were employed to separate ⁴¹Ca from interferences. The method relies on the differences in the solubility of the generated products. The behavior of Ca and the interfering elements such as Fe, Ni, Co, Eu, Ba, and Sr is examined at each separation step. The purified ⁴¹Ca was measured by a liquid scintillation counter, and the quench curve and counting efficiency were determined by using a certified reference material of known ⁴¹Ca activity. The recoveries in this study ranged from 56 to 68%, and the minimum detectable activity was 50 mBq g^-1 with 0.5 g of concrete sample.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.243-244
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• 2013

Over the past 15 years, several groups have incorporated radio-frequency quadrupole (RFQ) based instruments before the accelerator in accelerator mass spectrometry (AMS) systems for ion-gas interactions at low kinetic energy (＜40 eV). Most AMS systems arebased on a tandem accelerator, which requires negative ions at injection. Typically, AMS sensitivity abundance ratios for radioactive-to-stable isotope are limited to Xr/Xs ＞10^-15, and the range of isotopes that can be analyzed is limited because of theneed to produce rather large negative ion beams and the presence of atomic isobaric interferences after stripping. The potential of using low-kinetic energy ion-gas interactions for isobar suppression before the accelerator has been demonstrated for several negative ion isobar systems with a prototype RFQ system incorporated into the AMS system at IsoTrace Laboratory, Canada (Ontario, Toronto). Requisite for any such RFQ system applied to very rare isotope analysis is large transmission of the analyte ion. This requires proper phase-space matching between the RFQ acceptance and the ion beam phase space (e.g. 35 keV, ${\varphi}3mm$, +-35 mrad), and the ability to control the average ion energy during interactions with the gas. A segmented RFQ instrument is currently being designed at Korea Institute for Science and Technology (한국과학기술연구원, KIST). It will consist of: a) an initial static voltage electrode deceleration region, to lower the ion energy from 35 keV down to ＜40 eV at injection into the first RFQ segment; b) the segmented quadrupole ion-gas interaction region; c) a static voltage electrode re-acceleration region for ion injection into a tandem accelerator. Design considerations and modeling will be discussed. This system should greatly lower the detection limits of the 6 MV AMS system currently being commissioned at KIST. As an example, current detection sensitivity of 41Ca/Ca is limited to the order of 10^-15 while the 41Ca/Ca abundance in modern samples is typically 41Ca/Ca~10^-14 - 10^-15. The major atomic isobaric interference in AMS is 41K. Proof-of-principal work at IsoTrace Lab. has demonstrated that a properly designed system can achieve a relative suppression of KF3-/41CaF3- ＞4 orders of magnitude while maintaining very high transmission of the 41CaF3- ion. This would lower the 41Ca detection limits of the KIST AMS system to at least 41Ca/Ca~10^-19. As Ca is found in bones and shells, this would potentially allow direct dating of valuable anthropological archives and archives relevant to our understanding of the most pronounced climate change events over the past million years that cannot be directly dated with the presently accessible isotopes.

• 방사성폐기물학회지
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• 제17권1호
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• pp.121-126
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• 2019

원자력발전소 해체과정에서 방사화 재고량에 대한 평가는 방사선 환경에 정보를 제공함으로써 해체 계획을 수립하는데 중요한 정보를 제공한다. 원자로 운전 정지 후 원자로 및 관계시설에서의 축적된 방사능은 노심 구조물, 반사체 및 차폐체 등의 구조재가 중성자 조사에 의해 방사화된것이다. 방사화생성물 중 $^{36}Cl$ 과 $^{41}Ca$ 은 반감기와 화학적 물리학적 특성에 의해 해체 처분 관점에서 매우 중요한 핵종이며 이에 따라 본 연구에서는 차폐 콘크리트 내 생성량을 평가하였다. MCNPX 코드를 사용하여 중성자속과 반응단면적을 계산하였으며 이 결과를 토대로 ORIGEN2 코드를 사용하여 방사화생성물의 양을 평가하였다.

• Journal of Nutrition and Health
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• 제34권1호
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• pp.54-61
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• 2001

The Ca and P balance studies were carried out with two different diets varying Ca levels : the current Korean RDA level(normal Ca diet) and the high level (High Ca diet) which was determined by adding 2SD to mean Ca intake of all subjects. The subjects were sever healthy adult woman, aged from 25 to 32 years old. The metabolic studies were conducted for two weeks with a days recess in between : during the fist week with normal Ca diet and during the second week with high Ca diet. The composition of nutrients excepting Ca of both diets was similar to subjects usual intake. The result were summarized as follows: Mean daily Ca intake was 728.8mg from norma Ca diet and 945.5mg from high Ca diet. Fecal excretion of Ca increased significantly(p<0.05) on high Ca diet, but urinary excretion of Ca did not show any differences between the two diet periods. There were also no significant differences in Ca retention between the two diet periods but it tended to be greater during high Ca diet period: 112.1mg/day during normal Ca diet period vs 208.2mg/day during high Ca diet period. Mean apparent Ca absorption was 41.2% on normal Ca diet and 42.1% on high Ca diet, indicating it was not affected by high Ca intake level used in this study. On the contrary, P retention was significantly increased up to 109.4mg/day with high Ca diet as compared to- 41mg/day with normal Ca diet. There were no significant differences in fecal and urinary excretion of P but those to be lower during high Ca diet period. The above results showed that higher Ca intake more than current RDA(700mg/day), in the level of 945.5mg/day, could increase Ca retention through Ca absorption comparable to the rate appeared on RDA level intake. P retention was also improved by high Ca intake. Therefore, higher Ca intake than the current RDA level seemed to produce favorable effects on bone health in adult women. However, the current RDA level seemed to be relatively appropriate, considering the results that all the subjects but one maintained positive Ca balance with normal Ca diet. (Korean J Nutrition 34(1):54-61, 2001)

• 한국멀티미디어학회논문지
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• 제11권8호
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• pp.1111-1120
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• 2008

셀룰러 오토마타(CA: cellular automata)의 특징 중에서 확산과 국소적인 상호 작용(Local Interaction)은 암호시스템을 설계하는데 적합하여 암호 알고리즘, 의사난수 생성기를 비롯한 암호시스템의 설계 논리로 활용되고 있다. 국내에서는 2002년 CA 기법을 이용한 128 비트 블록 암호(CAB1)가 처음으로 소개되었고, CEC'04에서는 가역 CA를 이용한 64 비트 블록 암호(CAB2)가 제안되었다. 본 논문에서는 두 알고리즘이 각각 차분 공격과 통계 분석에 취약함을 보인다. 먼저, $2^{31.41}$의 선택 평문을 이용하여 $2^{13.41}$의 공격 복잡도를 갖는 CAB1에 대한 차분 공격을 소개한다. 그리고 CAB2는 제안 논문에서 224 비트의 안전성을 갖는다고 제안되었지만, CAB2의 키가 균일 성질을 만족해야만 하는 취약점을 이용하여 184 비트의 안전성만을 가짐을 보인다. 본 논문에서 제안하는 공격 결과는 이 CA 기반 블록 암호들에 대한 첫 번째 분석 결과이다.

• 오리마을
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• 통권162호
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• pp.41-41
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• 2016

• BMB Reports
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• 제41권1호
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• pp.86-91
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• 2008

The full-length cDNA of CaAbsi1 encodes a presumptive protein of 134 amino acid residues that has homology to a putative zinc finger protein in its C-terminus. The deduced amino acid sequence has 50% homology to Oryza sativa NP001049-274, the function of which is unknown. Expression of CaAbsi1 was reduced in response to inoculation of non-host pathogens. On the other hand it was induced one hour after exposure to high concentrations of NaCl or mannitol, and six hours after transfer to low temperature. Induction also occurred in response to oxidative stress, methyl viologen, hydrogen peroxide and abscisic acid. Our results suggest that CaAbsi1 plays a role in multiple responses to wounding and abiotic stresses.

• BMB Reports
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• 제41권11호
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• pp.771-777
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• 2008

Calmodulin (CaM) proteins, members of the EF-hand family of $Ca^{2+}$-binding proteins, represent important relays in plant calcium signals. Here, OsCam1-1 was isolated by PCR amplification from the rice genome. The gene contains an ORF of 450 base pairs with a single intron at the same position found in other plant Cam genes. A promoter region with a TATA box at position-26 was predicted and fused to a gus reporter gene, and this construct was used to produce transgenic rice by Agrobacterium-mediated transformation. GUS activity was observed in all organs examined and throughout tissues in cross-sections, but activity was strongest in the vascular bundles of leaves and the vascular cylinders of roots. To examine the properties of OsCaM1-1, the encoding cDNA was expressed in Escherichia coli. The electrophoretic mobility shift when incubated with $Ca^{2+}$ indicates that recombinant OsCaM1-1 is a functional $Ca^{2+}$-binding protein. In addition, OsCaM1-1 bound the CaMKII target peptide confirming its likely functionality as a calmodulin.

• Journal of Nutrition and Health
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• 제41권3호
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• pp.206-215
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• 2008

The purpose of this study was to investigate the effect of manganese (Mn) supplementation on bone status and calcium balance in ovariectomized rats according to the calcium intake levels. Total of 50 Sprague Dawley female rats (6 weeks) were divided into 5 groups and bred for 12 weeks: sham operated control group (SACa), OVX Ca deficiency group (OLCa) with Ca deficiency diet (0.1% Ca modified AIN-93N diet), OVX Ca deficiency & Mn supplement group (OLCaMn), OVX adequate Ca group (OACa; 0.5% Ca AIN-93N diet) and OVX adequate Ca & Mn supplement group (OACaMn). BMD (bone mineral density) of the femur was increased by Mn supplementation in OVX adequate Ca group. However, BMDs of spine, femur and tibia were lowered in OLCa compared to the OLCaMn group. Bone strength of tibia in OLCaMn group was significantly lower than OLCa group. Serum ALP (alkaline phosphatase) and CTx (C-telopeptide of collagen cross-links) levels were significantly higher in ovariectomized rats than those in the sham group, but they were not changed by Mn supplementation. Ca retention rate and Ca absorption rate did not differ among the experimental groups. Urinary Ca excretion was increased by Mn supplementation in Ca deficiency rats. In summary, Mn supplementation resulted in positive effects on bone mineral density ovariectomized rats with which intake adequate Ca. However, Mn supplementation on Ca deficiency ovariectomized rats resulted in decrement of BMO and bone strength by increasing Ca excretion. Therefore, it is encouraged to consider calcium intake levels in supplementation of manganese in order to prevent postmenopausal osteoporosis and to keep bone healthy. (KoreanJNutr2008; 41(3): 206~215)