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        검색결과 17

        1.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the current study, we investigated the inhibitory activity of water soluble β-glucan from oat (Avena sativa) against various digestive enzymes such as α-glucosidase, sucrase, maltase and glucoamylase. Inhibition of these enzymes involved in the absorption of disaccharide can significantly decrease the post-prandial increase of blood glucose level after a mixed carbohydrate diet. The β-glucan had the highest documented rate of small intestinal sucrase inhibitory activity (2.83 mg/mL, IC50) relevant for potentially managing post-prandial hyperglycemia. Furthermore, we evaluated the effects of β-glucan on the level of post-prandial blood glucose in animal model. The post-prandial blood glucose levels were tested two hours after sucrose/starch administration, with and without β- glucan (100, and 500 mg/kg-body weight). The maximum blood glucose levels (Cmax) of β-glucan administration group were decreased by about 23% (from 219.06±27.82 to 190.44±13.18, p<0.05) and 10% (from 182.44±13.77 to 165.64±10.59, p<0.01) in starch and sucrose loading test, respectively, when compared to control in pharmacodynamics study. The β -Glucan administration significantly lowered the mean, maximum, and minimum level of post-prandial blood glucose at 30 min after meal. In view of the foregoing, it is felt that our findings suggest that β-glucan from oat serves to reduce post-prandial blood glucose rise secondary to slower absorption of glucose in the small intestine, via carbohydrate hydrolyzing enzymes inhibition.
        4,000원
        2.
        2017.05 구독 인증기관·개인회원 무료
        For possibility of specific gas sieve and adsorption, metal organic framework has attracted expectation in the gas separation field. But, this enhances gas transport performance only at high loading. So we designed effective composite growing MOF on porous 2D template to improve membrane at low concentration. The mixed matrix membranes showed improved CO2 permeability drastically by improved CO2/N2 diffusion selectivity and showed anti-plasticization effect.
        3.
        2016.11 구독 인증기관·개인회원 무료
        Facilitated transport membranes in the solid state have been attractive because they can improve both the permeability and the selectivity simultaneously to overcome the trade-off behavior. The carrier activity for facilitated transport plays a key role in determining separation performance. We have reported the solid-state facilitated transport membranes containing surface-activated Ag nanoparticles (NPs) as an olefin carrier for separation of olefin/paraffin mixtures, particularly propylene/propane mixture. Interestingly, the surface positive charge density of Ag atom in Ag NPs was linearly correlated with the propylene solubility and also with the propylene/propane selectivity. In addition, the separation performance has been maintained unchanged up to 500 hours.
        4.
        2016.05 구독 인증기관·개인회원 무료
        In olefin/paraffin separation process, new technology such as membrane separation process has been ever demanding for both economic and environmental reasons. facilitated olefin transport membrane, containing positively charged silver nanoparticles (Ag NPs) by electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) as olefin carriers dispersed in poly(vinyl pyrrolidone) (PVP), shows extremely high separation performance for propylene/propane mixtures. However, higher permeance is always demanding for practical applications. In this study, POSSs were added to PVP/Ag NPs/TCNQ membranes. Among various kinds of POSS, trisilanolisooctyl POSS showed higher permeance with a moderate selectivity. Therefore it is concluded that mesoporous POSS is an effective additive in improving the gas permeance.
        5.
        2016.05 구독 인증기관·개인회원 무료
        Facilitated olefin transport membrane, containing positively charged silver nanoparticles (AgNPs) as olefin carriers dispersed in poly(vinyl pyrrolidone) (PVP), leads extremely high separation performances for propylene/propane mixtures. In this study, as representatives of electron withdrawing nitrobenzene compounds, 1,2-dinitrobenzene (DNB) and 3,4-dinitro toluene (DNT) were used for PVP/AgNPs membranes. The correlation between the surface charge density of AgNPs and the separation performance was investigated with X-ray photoelectron spectroscopy (XPS). A fairly good linear correlation between the surface charge density and the separation performance was confirmed, which meant that the positive charge density on the surface of AgNPs may be a key factor in determining the separation performance of facilitated olefin transport membranes.
        6.
        2016.05 구독 인증기관·개인회원 무료
        CO2 capture technologies have been highlighted over the past decades because of global warming. Among the various technologies for CO2 capture, facilitated CO2 transport membranes show high CO2 selective performance by introducing carrier which interacts with CO2. In this presentation, we prepared and investigated facilitated CO2 transport membrane comprising potassium bis[(trifluoromethyl)sulfonylimide] (TF2N) dissolved in a polymer matrix of Pebax1657. Adding potassium salt to the membrane shows further improvement in gas permeabilities while maintaining or even improving the gas selectivity, compared to the corresponding neat polymer membrane. Therefore, we have demonstrated that KTF2N can act as dual carrier for CO2 and its facilitated transport membrane could be very effective in enhancing the CO2 separation performance.
        7.
        2015.11 구독 인증기관·개인회원 무료
        Reduction in the amount of Ag salts in the membranes is required for practical applications in the industry. However, since the separation performance is directly related to the amount of Ag salts, it has been difficult to reduce the amount of Ag salts. In this study, we succeeded in preparing polymer/Ag salts/Al(NO3)3 membranes with 30% reduction in the amount of Ag salts by utilizing KIT-6, which is a porous material. When KIT-6 was incorporated into the polymer/Ag salts/Al(NO3)3 membrane, the separation performance for propylene/propane mixed gas increased with a propylene over propane selectivity of 20 and mixed gas permeance of 10 GPU. The enhanced separation performance is attributed to both the coordination of hydroxyl groups in KIT-6 with Ag ions and the porous properties of KIT-6.
        8.
        2015.11 구독 인증기관·개인회원 무료
        Polymer electrolyte membranes consisting of a PVP/AgCF3SO3/Al(NO3)3 complex were prepared for the separation of a propylene/propane mixture. In this study, the effect of Al(NO3)3 on inhibiting the reduction of silver ions generated from AgCF3SO3 was investigated, where AgCF3SO3 was used as a cost-effective alternative to AgBF4 in the facilitated olefin transport membranes. When Al(NO3)3 was incorporated into a PVP/AgCF3SO3 complex membrane, the selectivity of propylene/propane and mixed gas permeance showed 5 and 0.5GPU, respectively. Moreover, the PVP/AgCF3SO3/Al(NO3)3 complex membranes showed long-term stability although AgCF3SO3 is easily reduced to silver nanoparticles. It was thus proved that Al(NO3)3 played the role of a retardant for the reduction of silver ions generated from AgCF3SO3 as well as from AgBF4.
        9.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to examine the quality characteristics and antioxidant activity of yogurt containing hot water extract from maca. Four different levels (0, 4, 8, 12%) of maca extract were added to milk followed by fermentation with lactic acid bacteria at 37℃ for 12 hrs, and then the physicochemical properties of the samples were investigated. During 7 days of storage at 4±1℃, the acid production (pH and titratable acidity) of the yogurt increased with the addition of maca extract. The Hunter L value (lightness) decreased, while the b value (yellowness) increased as the maca extract level in the yogurt increased. Viable cell counts were not significantly different among the samples. The results of consumer acceptance tests showed that no significant differences in overall acceptability were observed between the yogurts containing 4% and 8% of maca extract and a control yogurt. The yogurt containing maca extract exhibited higher DPPH radical and superoxide anion radical scavenging activities than the control yogurt over the storage period.
        4,000원
        10.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        은 고분자 전해질은 올레핀/파리핀 혼합물 분리에 매우 효과적인 분리막 재료이다. 이는 고분자 매질속에 녹아 있는 은이온이 올레핀과 선택적, 가역적 반응을 통해 올레핀만을 분리막속으로 통과시키기 때문이다. 그러나 이러한 은 고분자 전해질 분리막은 실제 공정에 응용되기에는 다소 약한 장시간 운전 성능 안정성을 보인다. 즉 분리 성능이 시간이 지남에 따라 점차 감소되는데 이는 은이온이 은 나노입자로 환원되기 때문이다. 따라서 본 연구에서는 poly(vinyl pyrrolidone) (PVP)와 AgBF4로 이루어진 고분자 전해질막의 안정성을 향상시키고자 비이온 계면활성제인 C18H35(OCH2CH2)20OH (Brij98)를 첨가제로 사용하였다. 분리막속에서 은이온의 은 나노입자로의 환원현상을 원자전자 현미경과 자외선 분광학을 이용하여 분석하였다. 그 결과 Brij98이 첨가된 분리막의 경우 은 나노입자의 성장이 늦춰졌으며, 프로판/프로핀렌 선택도가 장시간 유지됨을 알 수 있었다.
        4,000원
        11.
        2005.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dye-sensitized solar cells(DSSCs) have been under investigation for the past decade due to their attractive features such as high energy conversion efficiency and low production costs. The basis for energy conversion in the injection of electrons from a photoexcited stateof a dye sensitizer into the conduction band of the nanocrystalline semiconductor upon absorption of light. It is believed that the DSSC is one of the most promising technologies to solve the significant energy problems. In this article, the development trends and perspective of DSSCs were reviewed.
        4,000원
        12.
        1997.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        기체 투과도 및 기계적 강도가 높은 고분자 비대칭막을 상분리법으로 제조하기 위해 막 제조 메카니즘을 규명하는 연구를 수행하였다. 기본적인 연구가 많이 이루어진 폴리스티렌, 이에 비해 용매와의 관계가 덜 알려져 있는 폴리아미드이미드인 Torlon과 3,3'4,4'-benzophenontetracarboxylic diahmydride와 1,4-phenylene diarnine로 이루어진 폴리이미드를 여러 용매에 녹여 얻어진 캐스팅 용액으로부터 비대칭막을 제조하였다. 용매와 비용매와의 혼합열과 막 구조의 관계로부터, 막의 구조를 결정하는 데에는 용매와 비용매의 혼합열이 크게 영향을 미침을 알 수 있었다. 이 결과로부터 폴리술폰 막의 구조를 용매 첨가제를 사용하여 조절하였다. 캐스팅 고분자 용액이 비용매를 만날 때 용매와 비용매와의 혼합열이 두 물질의 교환 속도에 영향을 미쳐 결국에는 막의 구조에 영향을 미치는 데에 대한 이론적인 고찰도 아울러 수행하였다.
        4,000원
        13.
        1992.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was divised to observe the inhibitory effect of growth rate of human colon cancer cells by Eucommial leaf extract, in vitro. Three species of human colon cancer cells, HRT-18, HCT-48 and HT-29, were used for the experiment. Each extract of Ecommial leaf was prepared by extraction with water, 95% alcohol, acetone, chloroform and petroleum ether, and then the inhibitory effect of each extract on the growth rate of cells was compared with control group and each other. The expermental results obtained are summarized as follows ; 1. Inhibitory effects on growth rate of human colon cancer cells were strongest in the petroleum ether extract and next in the chloroform extract. 2. Inhibitory effects on the growth rate of the cancer cells by extracts of water, 95% alcohol and acetone were weaker than that of petroleum ether and chloroform. 3. Inhibitory effect of each extract on the cancer cell growth was shown most strong activity in HT-29, and was in order of HRT-18 and HCT-48. In view of the results, it could be suggested that inhibitory effects of non-polar solvent`s extracts against the cancer cell growth were more stronger than that of polar solvents and the effects were indicated defference according to the species of the cells.
        4,000원
        14.
        2012.06 KCI 등재 서비스 종료(열람 제한)
        강화제는 손상된 석조문화재를 보존하기 위해 널리 사용되고 있다. 본 연구에서는 기 개발된 표면 강화제를 화강암, 사암, 대리암에 적용시킨 후 암석 광물학적 특성변화를 연구하기 위하여 개발된 강화제를 화강암, 대리암, 사암에 적용하여 강화제의 효율에 대한 현장평가를 실시하였다. 강화제 현장 적용 대상암석에 대하여 X-선회절분석, 쌍안실체현미경, 편광현미경, 주사전자현미경 관찰 등을 실시하였으며, 본 연구에 사용한 강화제는 개발한 2종 100%1T1G, 3%40nm/97%1T1G이다. 개발 강화제 처리 후 암석 표면변화에 대한 연구 결과에 의한 효과는 화강암의 경우 3%40nm/97%1T1G가 아주 우수하고, 사암의 경우 3%40nm/97%1T1G 약간 우수하며, 대리암의 경우 3%40nm/97%1T1G와 100%1T1G는 유사하다. 강화제 처리 전후의 특성은 각 강화제에 따라 다르며 향후 손상된 석조문화재에 강화제를 처리할 경우 이 연구 결과를 적용할 수 있을 것으로 생각된다.
        15.
        2011.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구에서는 마카 열수 추출액을 다양한 수준(0%, 8%, 16%, 24% 및 32%)으로 첨가하여 음료를 제조한 후 품질 특성을 살펴보고 및 에서 4주간 저장하면서 항산화능의 변화를 분석하였다. 마카 음료의 pH는 마카 추출액 첨가군이 대조군보다 낮게 나타났고 는 높게 나타났다. 색도측정 결과 마카 추출액 첨가량이 증가할수록 명도는 감소하였고 적색도는 증가하였다. 소비자 기호도 검사결과 대조군과 비교하여 24% 첨가군까지 전반적인 바람직성에
        16.
        2010.04 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        음료 베이스용 시럽을 개발하기 위하여 마카 추출액을 다양한 수준(0%, 7%, 14%, 21%, 28%)으로 첨가하고 품질 특성 및 항산화활성을 측정하였다. pH는 대조군보다 첨가군이 낮았고 시럽의 당도는 시료간에 유의적인 차이가 없었으며 점도는 마카추출액의 농도가 증가할수록 증가하였다. 명도를 나타내는 L값은 마카 추출액의 첨가비율이 증가할수록 감소하였고 b값은 증가하였다. 기호도 검사 결과 향, 단맛 및 전반적인 기호도면에서 시료간에 유의적인