• Bulletin of the Korean Chemical Society
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• 제19권1호
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• pp.39-44
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• 1998

$LiCoO_2$ powder was synthesized in an aqueous solution by a sol-gel method and used as a cathode active material for a lithium ion rechargeable battery. The layered $LiCoO_2$ powders were prepared by igniting in air for 12 hrs at 600 ℃ $(600-LiCoO_2)$ and 850 ℃ $(850-LiCoO_2)$. The structure of the $LiCoO_2$ powder was assigned to the space group R bar 3 m (lattice parameters a=2.814 Å and c=14.04Å). The SEM pictures of $600-LiCoO_2$ revealed homogeneous and fine particles of about 1 μm in diameter. Cyclic voltammograms (CVs) of $600-LiCoO_2$ electrode displayed a set of redox peaks at 3.80/4.05 V due to the intercalation/deintercalation of the lithium ions into/out of the $LiCoO_2$ structure. CVs for the $850-LiCoO_2$ electrode had a major set of redox peaks at 3.88/4.13 V, and two small set of redox peaks at 4.18/4.42 V and 4.05/4.25 V due to phase transitions. The initial charge-discharge capacity was 156-132 mAh/g for the $600-LiCoO_2$ electrode and 158-131 mAh/g for the $850-LiCoO_2$ electrode at the current density of 0.2 mA/cm2. The cycleability of the cell consisting of the $600-LiCoO_2$ electrode was better than that of the $850-LiCoO_2$. The diffusion coefficient of the $Li^+$ ion in the $600-LiCoO_2$ electrode was calculated as $4.6{\times}10^{-8}\; cm^2/sec$.

• Nuclear Engineering and Technology
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• 제37권4호
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• pp.375-384
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• 2005

To investigate the flow-accelerated corrosion (FAC) dependency of carbon steel (A106 Gr. B) and low-alloy steels (1Cr-1/2Mo, 21/4Cr-1Mo) on pH, orifice distance, and material, experiments were carried out. These experiments were performed using a flow velocity of 4 m/sec (partly 9 m/sec) at pH $8.0\~10.0$ in an oxygen-free aqueous solution re-circulated in an Erosion-Corrosion Test Loop at $130^{\circ}\;{\ldots}$ for 500 hours. The weight loss of the carbon steel specimens appeared to be positively dependent on the flow velocity. That of the carbon and low-alloy steel specimens also showed to be distinguishably dependent on the pH. At pH levels of $8.0\~9.5$ it decreased, but increased from 9.5 to 10.0. Utility water chemistry personnel should carefully consider this kind of pH dependency to control the water system pH to mitigate FAC of the piping system material. The weight loss of the specimens located further from the orifice in the distance range of $6.8\~27.2$ mm was shown to be greater, except for 21/4Cr-1Mo, which showed no orifice distance dependency. Low alloy steel specimens exhibited a factor of two times better resistance to FAC than that of the carbon steel. Based on this kind of FAC dependency of the carbon and low-alloy steels on the orifice distance and material, we conclude that it is necessary to alternate the composition of the secondary piping system material of NPPs, using low-alloy steels, such as 21/4Cr-1Mo, particularly when the system piping has to be replaced.

• 약학회지
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• 제42권1호
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• pp.59-69
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• 1998

To increase the solubility of quercetin, which is a practically insoluble flavonoid of Ginkgo biloba leaf, the effects of nonaqueous vehicles. Their cosolvents, water-sol uble polymers and modified cyclodextrins (CDs) were observed. Polyethylene glycols, diethyleneglycol monoethyl ether, and their cosolvents with water showed a good solvency toward quercetin. Also the aqueous solutions of povidone, copolyvidone and Cremophor RH 40 was effective in solubilizing quercetin. Complex formation of quercetin with ${\beta}$-cyclodextrin (${\beta}$-CD), dimethyl-${\beta}$-cyclodextiin (DMCD), 2-hydroxypropyl-${\beta}$-cyclodextrin (HPCD) and ${\beta}$-cyclodextrin sulfobutyl ether (SBCD) in water was investigated by solubility method at $37^{\circ}C$. The addition of CDs in water markedly increased the solubility of quercetin with increasing the concentration. AL type phase solubility diagrams were obtained with CDs studied. Solubilizaton efficiency by CDs was in the order of SBCD >> DMCD > HPCD > ${\beta}$-CD. The dissolution rates of quercetin from solid dispersions with copolyvidone, povidone and HPCD were much faster than those of drug alone and corresponding physical mixtures, and exceeded the equilibrium solubility (3.03${\pm}1.72{\mu}$g/ml). The permeation of quercetin through duodenal mucosa did not occur even in the presence of enhancers such as bile salts, but the permeation was observed when the mucus layer was scraped off. This was due to the fact that quercetin had a strong binding to mucin ($58.5{\mu}$g/mg mucin). However rutin was permeable to the duodenal mucosa. The addition of enhancer significantly increased the permeation of rutin in the order of sodium glycocholate.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권6호
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• pp.80-90
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• 2014

The laboratory and field studies were conducted to identify an optimal injection concentration of nanoscale zero-valent iron particles (NZVI) and to evaluate the applicability of NZVI-based reactive zone technology to the site contaminated with trichloroethylene (TCE) DNAPL (Dense Non-Aqueous Phase Liquid). The laboratory test found an optimal injection concentration of NZVI of 5 g/L that could remove more than 95% of 0.15 mM TCE within 20 days. Eleven test wells were installed at the aquifer that was mainly composed of alluvial and weathered soils at a strong oxic condition with dissolved oxygen concentration of 3.50 mg/L and oxidation-reduction potential of 301 mV. NZVI of total 30 kg were successfully injected using a centrifugal pump. After 60 days from the NZVI injection, 86.2% of the TCE initially present in the groundwater was removed and the mass of TCE removed was 405 g. Nonchlorinated products such as ethane and ethene were detected in the groundwater samples. Based on the increased chloride ion concentration at the site, the mass of TCE removed was estimated to be 1.52 kg. This implied the presence of DNAPL TCE which contributed to a higher estimate of TCE removal than that based on the TCE concentration change.

• 한국산학기술학회논문지
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• 제20권4호
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• pp.420-427
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• 2019

이 연구의 목적은 바디로션 제조 시 화장품 첨가제로서의 덕구온천수를 평가하기 위함이다. 주요 수용성 구성성분으로서의 온천수의 적합성을 시험하였다. 온천수의 미생물 및 화학적 안전성 시험이 수행되었다. 대장균을 비롯한 미생물은 검출되지 않았거나 검출한도 이하로 검출되었으며, 유해한 중금속은 전혀 검출되지 않았다. 온천수의 세포독성이 평가되었으며, 온천수의 pH 변화를 3달 동안 측정하였다. 또한 덕구온천수 및 증류수로 제조된 바디로션에 대해서 관능시험을 수행함으로써 소비자의 적합성을 관능특성 분석을 통하여 평가하였다. 증류수로 제조된 바디로션보다 온천수를 사용한 바디로션을 피부에 적용하였을 때, 피부보습, 피부트러블 및 피부 장벽강화가 증진되었다. 종합해 보았을 때, 이 연구의 결과는 화장품 제조에 있어서 온천수를 사용하는 것은 화장품의 효능을 증진시킬 수 있음을 보여 준다.

• 한국환경과학회지
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• 제28권2호
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• pp.183-189
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• 2019

Curcumin ($C_{21}H_{20}O_6$) is a hydrophobic polyphenol found in turmeric. Although curcumin has been used as a natural medicine, its major limitation is related to poor absorption from the gut. Therefore, we developed a method for preparation of Curcumin Nanospheres (CN) to improve the aqueous-phase solubility of curcumin and investigate the functional role of CN in promoting feed efficiency and odor reduction in mice. CN showed inhibitory effects on actate dehydrogenase (LDH) cytotoxicity induced by ecotoxic substance toluene in gut epithelial HCT116 cells. In addition, the weights of internal organs (liver, heart, kidneys, and spleen) and the levels of serum Glutamate Oxaloacetate Transaminase (GOT), Glutamate Pyruvate Transaminase (GPT), and LDH did not show significant differences between mice administered oral CN for two weeks and compared to the control group. Interestingly, CN not only reduced hydrogen sulfide ($H_2S$) and ammonia ($NH_3$) levels and fecal odor, but also improved feed efficiency in mice. These results demonstrate that oral nano-delivery of anti-ecotoxicological CN is a functional system to deliver curcumin to the gut to improve feed efficiency and reduce fecal odor in mice.

• 생약학회지
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• 제50권1호
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• pp.65-71
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• 2019

One of the oriental medicine prescriptions, Sagunja-tang consists of four herbal medicines (Ginseng Radix, Poria Sclerotium, Atractylodis Rhizoma Alba, and Glycyrrhiziae Radix et Rhizoma) and has been used as a medicine to enhance tonify the function of spleen and stomach in Korea. In this study, we conducted simultaneous analysis of the 9 marker components, liquiritin apioside, liquiritin, ginsenoside Rg1, liquiritigenin, ginsenoside Rb1, glycyrrhizin, atractylenolide III, atractylenolide II, and atractylenolide I in Sagunja-tang using a liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). Marker compounds were separated on a Waters Acquity UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, 1.7 mm) and the column was maintained at $45^{\circ}C$. The mobile phase consists of 0.1% (v/v) aqueous formic acid and acetonitrile with gradient condition. The LC-MS analysis was performed using a Waters ACQUITY TQD LC-MS/MS system with multiple reaction monitoring (MRM) method in the positive and negative modes. The calibration curves of the nine marker components showed good linearity with coefficient of determination ${\geq}0.9984$ within tested range. The limits of detection and limits of quantification values were 0.27-2.42 ng/mL and 0.81-7.27 ng/mL, respectively. The concentrations of tested 9 analytes in the lyophilized Sagunja-tang sample using the established LC-ESI-MS/MS MRM method were detected up to 16.593 mg/g. These results can be useful as a basic data for the quality control of an oriental medicine prescriptions.

• 한국식품영양학회지
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• 제31권6호
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• pp.957-963
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• 2018

Deoduk (Codonopsis lanceolata) has a complex chemical composition that includes polyphenols, saponins, amino acids, and other unidentified compounds. The contents of tangshenoside and lobetyolin are considered as standard of quality evaluation of Deoduk. In this study, an ultra-performance liquid chromatography (UPLC) method was developed for the quantitative determination of the two marker constituents, tangshenoside and lobetyolin. The methods for determining the standards of quality were validated by measuring their linearity, specificity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy using UPLC. Reversed-phase UPLC analysis was conducted quantitatively to identify individual tangshenoside and lobetyolin in Deoduk extracted with 50% (v/v) aqueous ethanol. We used 21 samples to carry out quantitative analysis of tangshenoside and lobetyolin. Based on their dry weights, the levels of tangshenoside and lobetyolin were 0.36~3.54 mg/g, 0.24~1.29 mg/g, respectively. These results will be valuable as basic data for standardization of Korean Deoduk.

• 자원환경지질
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• 제53권6호
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• pp.677-685
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• 2020

우스키 마애불상군의 모암은 아소-4 화산쇄설암층군에 속하는 암회색 응회암이다. 이 불상군은 상부에서 유입되는 강수와 지반에서 상승하는 지하수로 인한 백화현상과 암반의 토양화가 상당히 진행되어 보존대책이 시급한 상태였다. 불상군 표면 염풍화의 주요 원인인 백색오염물에서는 세나다이트, 석고, 백운석이 동정되었다. 이들의 용출실험 결과, 세나다이트는 교반초기에 용해되었다가 4시간 이후 재용출되고, 석고는 2시간 교반까지 검출되다가 4시간 교반 후 용해되는 특성을 보였다. 백색오염물의 재결정 환경을 파악하기 위해 11개월간 미기후 환경을 모니터링한 결과, 봄철에는 세나다이트와 미라빌라이트의 상전이가 넓게 나타나고, 여름과 가을철에는 고온으로 인해 수용액 상태로 유지된다. 겨울철에는 온도가 하강하면서 미라빌라이트의 분포대가 가장 넓게 도시된다. 따라서 석불군 일대의 수분 이동통로를 차단하고 보호각 내에서 유지되는 다습한 환경을 제어하기 위한 초정밀 관측이 요구된다.

• 자원리싸이클링
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• 제30권4호
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• pp.64-74
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• 2021

원자력 발전 프로그램에 의해 세계 우라늄 메탈의 수요가 증가함에 따라 우라늄 메탈의 중요도는 날로 증가하고 있다. 이러한 우라늄 수요의 높은 증가로 인해 주로 바나듐을 비롯한 다른 원소들로부터 우라늄을 회수하고자 하는 새로운 추출법들이 더욱 중요하게 되었다. 본 연구에서는 kerosene에 희석된 상업용 아민 기반 추출제를 사용하여 황산 용액에서 우라늄(VI)과 바나듐(V)을 분리하는 방법을 다루었다. 0.005 ~ 5.0 mol/L농도의 황산 용액과 0.005 ~ 0.2 mol/L농도의 추출제를 사용하였다. 모든 실험은 25℃에서 30분동안 동일한 수상과 유기상의 비율(A:O = 1:1)로 수행하였다. 실험 결과 값으로부터 계산된 분리 계수(SF's)를 제시하고 모든 실험 값과 비교하였다.