• 방사성폐기물학회지
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• 제16권3호
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• pp.291-299
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• 2018

파이로 공정에서는 사용후핵연료 관리 공정 개발의 일환으로 산화 우라늄을 고온 용융염 전해질계에서 전기화학적 방법으로 환원시키기 위한 전해환원 공정이 개발되고 있다. 이에 따른 전해환원 공정의 반응기 설계를 위해서는 전기화학적 이론에 기초한 모델이 요구되고 있다. 본 연구에서는 상 분리를 설명하는 phase-field 이론에 기초하여 우라늄 산화물의 전해환원 모사를 위한 1차원 모델이 개발되었다. 모델은 우라늄 산화물 내 산소 원소의 확산과 펠렛 표면에서 전기화학 반응 속도를 나타내는 매개변수를 사용하여 외부로부터 내부로 진행되는 전해환원을 잘 모사하고 있으며 계산 결과 전체 전류는 산소원소의 내부 확산에 크게 의존하는 것으로 나타났다. 전해환원 반응에 대한 모델은 대용량 장치 설계에 최적화된 조건 도출에 활용될 것으로 예상되며 장치 설계가 완료되면 공정 연계 모사에 직접 사용될 것으로 기대된다.

• 한국안광학회지
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• 제15권4호
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• pp.313-317
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• 2010

목적: 이 연구 목적은 가공한 마그네슘 합금 AZ31 안경테를 plasma electrolytic oxidation(PEO) 표면 처리 후 표면특성에 대하여 조사하는 것이다. 방법: Plasma electrolytic oxidation(PEO) 표면 처리는 DC 전압을 변화시키며 처리하였고, 피막의 상 분석은 X-ray 회절기로 측정하였고, 형태학적 미세구조는 주사전자현미경로 관찰하였다. 그리고 피막층에 존재하는 원소의 농도를 에너지 분산 X-선 스펙트럼으로 조사하였다. 결과: PEO 처리시 전압이 증가함에 따라 XRD 측정 결과 MgO 피크가 증가하였으며, SEM 사진에서는 표면의 산화피막이 조밀하게 생기는 것을 확인 할 수 있었다. 그리고 EDS에서 성분의 변화도 일치함을 보여주었다. 결론: PEO 산화피막층은 전압이 증가 할수록 MgO 화합물의 형성이 점점 증가하기 때문에 산화막의 결정화가 진행되며, 65V에 60초 처리 시 표면상태, 접촉각, 내식성 시험에서 가장 좋은 결과를 보여 주었다.

• Journal of Microbiology and Biotechnology
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• 제27권8호
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• pp.1491-1499
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• 2017

Trimethylamine N-oxide (TMAO), which is transformed from trimethylamine (TMA) through hepatic flavin-containing monooxygenases, can promote atherosclerosis. TMA is produced from dietary carnitine, phosphatidylcholine, and choline via the gut microbes. Previous works have shown that some small molecules, such as allicin, resveratrol, and 3,3-dimethyl-1-butanol, are used to reduce circulating TMAO levels. However, the use of bacteria as an effective therapy to reduce TMAO levels has not been reported. In the present study, 82 isolates were screened from healthy Chinese fecal samples on a basal salt medium supplemented with TMA as the sole carbon source. The isolates belonged to the family Enterobacteriaceae, particularly to genera Klebsiella, Escherichia, Cronobacter, and Enterobacter. Serum TMAO and cecal TMA levels were significantly decreased in choline-fed mice treated with Enterobacter aerogenes ZDY01 compared with those in choline-fed mice treated with phosphate-buffered saline. The proportions of Bacteroidales family S24-7 were significantly increased, whereas the proportions of Helicobacteraceae and Prevotellaceae were significantly decreased through the administration of E. aerogenes ZDY01. Results indicated that the use of probiotics to act directly on the TMA in the gut might be an alternative approach to reduce serum TMAO levels and to prevent the development of atherosclerosis and "fish odor syndrome" through the effect of TMA on the gut microbiota.

• 대한의생명과학회지
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• 제11권3호
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• pp.365-373
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• 2005

The aim of this study was to investigate the alterations in meningeal blood flow by stimulation of trigeminovascular system. An open cranial window was prepared on the right parietal bone of male Sprague-Dawley rats. Trigeminovascular system was stimulated by electrical stimulation of trigeminal ganglion (ETS), somatosensory (whisker) stimulation, or topical applications of capsaicin and neuropeptides including substance P and calcitonin gene-related peptide (CGRP). Neonatal capsaicin pretreatment was performed with subcutaneous administration of capsaicin (50 mg/kg) within the first 24 hours after birth. Changes in regional blood flow of dural artery (rDBF) and pial artery (rPBF) were continuously measured through the cranial window by laser-Doppler flowmetry. Both ETS and capsaicin caused a chain of alterations in rPBF and rDBF responses, i.e., an immediate transient decrease followed by rapid and marked increase in rPBF, which were significantly attenuated not only by pretreatments with L-733,060, a $NK_1$ receptor blocker, $CGRP_{8-37}$, a $CGRP_1$ receptor blocker, and 7-nitroindazole monosodium salt (7-NINA), a neuronal nitric oxide synthase inhibitor but also by neonatal capsaicin treatment. Exogenous neuropeptides including substance P and CGRP increased the meningeal blood flow, which was significantly attenuated not only by pretreatment with L-733,060 and $CGRP_{8-37}$, respectively, but also by pretreatment with 7-NINA. The rPBF response to whisker stimulation was significantly attenuated not only by trigeminovascular system injuries including nasociliary nerve denervation and neonatal capsaicin treatment but also by pretreatments with L-733,060, $CGRP_{8-37}$ and 7-NINA. These results suggest that the stimulation of trigeminovascular system causes prominent alterations in meningeal blood flow, and that neuropeptides as well as nitric oxide in the trigeminovascular system are importantly implicated in the regulation of meningeal blood flow.

• 대한화학회지
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• 제22권1호
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• pp.37-44
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• 1978

$BH_3$-THF 용액에 염화리튬을 가한 새로운 환원계의 환원특성에 대한 연구가 대표적인 작용기를 가진 유기화합물을 가지고 표준조건($0^{\circ}$, THF)에서 이루어졌다. 조사 연구된 화합물중 벤조페논, 4가지 에스테르 및 시클로헥센은 $BH_3$ 환원과 별 차이를 보이지 않았으나, 2-헵탄온, 아세토페논, 염화벤조일, 프탈산무수물, 그리고 3가지 에폭시화물은 소량의 염화리튬에 의해 빠른 속도로 환원이 완결 되었다. 특히 에폭시화시클로헥센의 환원에 있어서는 소량의 염화리튬 존재하에서는 정량적으로 시클로헥산올을 생성하였으나 염화리튬의 양이 증가하면 2-클로로시클로헥산올이 시클로헥산올과 함께 생성됨을 알았다. 또한, 에폭시화시클로헥센과의 반응에 있어서 질산리튬은 염화리튬과는 달리 별로 효과가 없었다. 따라서 보란-염화리튬용액에 클로로수소화붕소리튬의 생성가능성을 논의하였다.

• 대한본초학회지
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• 제23권4호
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• pp.121-134
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• 2008

Objectives: Melia toosendan(MT) has been used as a traditional Korean herbal medicine, and today it is used as a medication for colic, side aches, heartache and other disorders of liver. The aim of this study was to determine whether fractionated extracts of MT inhibit free radical generation such as DPPH radical, superoxide radical and nitric oxide, production of nitrite, an index of NO, PGE2, iNOS, COX-2 and proinflammatory cytokines in lipopolysaccharide(LPS)-treated RAW 264.7 macrophages. Methods: MT extract prepared with methanol, and then fractionated with hexane, dichloromethane, ethylacetate, n-butanol and water. Inhibitory effect of MT onto free radical generation was determined by measuring DPPH, superoxide anions and nitric oxide scavenging activities in vitro. Cytotoxic activity of extracts on RAW 264.7 cells was measured using 5-(3-caroboxymeth-oxyphenyl)-2H-tetra-zolium inner salt(MTS) assay. Intracelluar oxidation was analysed by DCF-DA assay. The nitric oxide(NO) production was measured by Griess reagent system. The levels of iNOS and COX-2 expression were confirmed by western blot. And pro inflammatory cytokines were measured by ELISA kit. Results: Our results indicated that fractionated extracts, especially dichloromethane and ethyl acetate extracts, significantly inhibited free radical generation, the LPS-induced $H_2O_2$, NO, $PGE_2$ production and iNOS, COX-2 expression accompanied by an attenuation of TNF-${\alpha}$, IL-1${\beta}$ and IL-6 formation in macrophages. Conclusions: These results indicate that dichloromethane and ethyl acetate extracts of MT have potential as an agent of chronic inflammatory diseases.

• Corrosion Science and Technology
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• 제19권2호
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• pp.82-88
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• 2020

This work examined the corrosion protection performance of benzoate loaded hydrotalcite/graphene oxide (HT/GO-BZ) for carbon steel. HT/GO-BZ was fabricated by the co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, and scanning electronic microscopy. The corrosion inhibition action of HT/GO-BZ on carbon steel in 0.1 M NaCl solution was evaluated by electrochemical measurements. The benzoate content in HT/GO-BZ was determined by UV-Vis spectroscopy. Subsequently, the effect of HT/GO-BZ on the corrosion resistance of the water-based epoxy coating was investigated by the salt spray test. The obtained results demonstrated the intercalation of benzoate and GO in the hydrotalcite structure. The benzoate content in HT/GO-BZ was about 16%. The polarization curves of the carbon steel electrode revealed anodic corrosion inhibition activity of HT/GO-BZ and the inhibition efficiency was about 95.2% at a concentration of 3g/L. The GO present in HT/GO-BZ enhanced the inhibition effect of HT-BZ. The presence of HT/GO-BZ improved the corrosion resistance of the waterborne epoxy coating.

• 방사성폐기물학회지
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• 제8권1호
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• pp.49-56
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• 2010

Pyroprocessing에 의한 사용후핵연료 처리 과정에서 방사성 희토류 염화물이 포함된 폐용융염이 발생된다. 이러한 폐 용융염 내에 존재하는 방사성 희토류 염화물을 산화물로 침전시켜 회수함으로서 용융염을 재생할 수 있다. 최종적으로 발생되는 방사성 희토류 산화물의 저장과 처분에 적합한 monolithic 고화체를 제조하기 위한 연구를 수행하였다. 본 연구에서는 고상 소결에 의해 붕규산 유리에 의한 고화체 제조, 희토류 산화물을 모나자이트로 합성한 후 붕규산 유리에 의한 고화체 제조를 수행하였다. 또한 zinc titanate 세라믹이 주요성분인 고화 매질(ZIT)을 개발하여 고화체를 제조하였으며 각각의 고화체에 대한 침출 및 물리화학적 특성을 비교 평가하였다. 고상 소결에 의해 제조된 ZIT 매질 고화체는 내 침출성이 크며 밀도가 크고 열전도도가 우수한 특성을 나타내었다.

• 약학회지
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• 제57권4호
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• pp.282-288
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• 2013

Zinc oxide nanoparticles (ZnONPs) are widely used in a variety of products and cosmetic products including paper, paints, plastics and sunscreen. However, information on the safety of ZnONPs are not enough and many publications suggest possible toxic effects on environmental and human health. Furthermore, physico-chemical characteristics of nanoparticles makes it hard to test toxicity using the test guidelines of chemicals adopted by regulatory bodies. In this study, stability of ZnONPs was investigated using different types of isotonic solution, which is important in the toxicity study of intravenous route. Precipitation, aggregation, size, zeta potential and morphology of ZnONPs were evaluated with different times and concentrations. Precipitation of ZnONPs were observed in ionic isotonic solution including phosphate-buffered saline, Kreb's-Ringer solution, physiological salt solution and cell culture media of DMEM (Dulbecco's Modified Eagle's Medium) with 10% fetal bovine serum. On the other hand, they were stable without precipitation in non-ionic isotonic solution such as 5% glucose and 2% glycerol, respectively, which are biocompatible for intravenous injection. The average size of ZnONPs in 5% glucose and 2% glycerol was stably maintained, which is less than 30 nm and very similar as that in water dispersion of ZnONPs, provided by the manufacturer. The stability was maintained during the experimental period of 5 days and diluted state up to 15,000 ppm. These data suggest that 5% glucose and 2% glycerol solution can be used for the vehicles of ZnONPs in the toxicity study of intravenous injection route.

• 한방안이비인후피부과학회지
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• 제28권3호
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• pp.14-29
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• 2015

Objectives : The extract of Sagunja-tang has been traditionally used for restorative treatment of constitutional weakness, vascular and immune disorder, and nervous disease in Oriental country. This study investigated the regulatory effects of Sagunja-tang on the expression, production, and activity of immune mediators.Methods : In this study, the extract of Sagunja-tang was prepared by extracting with distilled water at 100$^{\circ}C$ for 2.5h. The extract was freeze-dried following filtration through 0.45${{\mu}m}$ filter. The extract was dissolved in Hank's balanced salt solution (HBSS) and filtered again through 0.45${{\mu}m}$ filter before use. The level of nitrite, an oxidative product of nitric oxide(NO) was measured in the culture medium by the Griess reaction. The levels of prostaglandin E₂(PGE₂), Th1 cytokines (IFN-${\gamma}$, IL-2) and Th2 cytokines(IL-4, IL-5, IL-13) were measured by enzyme-linked immunosorbent assay and the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression were determined by Western blot analysis. Also examined the effects of the extract on T-cell proliferation and cytotoxic activity of natural killer cells.Results : In this investigation, Production levels of Th2 cytokines (IL-4, IL-5, IL-13) was inhibited in a dose dependent manner by treatment with the extract. I also found that the extract increased T-cell proliferation and cytotoxic activity of natural killer cells in a dose-dependent manner.Conculsions : These results suggest that the water extract of Sagunja-tang may be useful for a therapeutic drug against a sickly constitution and immune diseases, probably by regulating the production of immune mediators.