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        검색결과 43

        41.
        2018.02 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This research aims to evaluate the current state of technology of enterprises in Vietnam in comparison with several countries in the AEC economic community, thereby to propose several recommendations to Vietnamese enterprises in order able to promote technology innovation activities, create competitiveness with enterprises in the region. Qualitative research methods are used through statistics and comparative descriptions from data collected from various sources: WEF, World Bank, CIEM, General Statistic Office. The study results show that Vietnamese enterprises still have many limitations in technology, originated from their small business scale (capital and labor), the current research capacity is still low, the funding for this activity is not high and the accessibility of the capital is still difficult. According to the Global Competitiveness Index, Vietnam's science and technology indexes are low compared to other AEC-developed countries including the availability of the latest technology; the acquisition of technology at the enterprise level; the capacity of improvement; quality of scientific research organizations..., which shall be a major barrier for Vietnamese enterprises to have to overcome to be able to create the competitiveness when entering the global market. From then on, the authors proposed solutions for two subjects, enterprises and government, to help Vietnamese enterprises to overcome this barrier.
        42.
        2017.05 서비스 종료(열람 제한)
        Background: Mahonia Nepalensis DC. (Hoang lien o ro), the specie of the family Berberidaceae, is widely distributed in the high mountainous areas at altitudes 1700 – 1900 m of Vietnam. It is found that the stem of Mahonia nepalensis indicated anti-inflammatory, anti-bacterial and antifungal activities and they are used particularly for the treatment of eczema, psoriasis, and other skin conditions. However, no study on the antioxidant and anti-cancer activities of Mahonia Nepalensis stem has been previously reported. The aim of this study was to evaluate anti-oxidant and anti-cancer activities of Mahonia Nepalensis stem. Methods and Results: The stem pieces of Mahonia Nepalensis were dried and extracted three times with 100% methanol. After that, the extract was suspended in distilled water and then partitioned with n-hexane, ethyl-acetate (EtOAc) and butanol (water saturated BuOH) fractions were then evaporated using a vacuum rotary evaporator. Evaluation of the anti-oxidative activity of Mahonia Nepalensis was carried out using a DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-producing system. The results revealed that the ethyl acetate fraction of M. nepalensis possessed higher potential DPPH radical scavenging activity (IC50, 81.88 ± 1.33㎍/㎖) than other fractions as well as BHT (2,6-Di-tert-Butyl-4-methylphenol) (IC50, 250.49 ± 1.60㎍/㎖). The reducing power assay was also investigated and EtOAc fraction showed higher absorbance values than other fractions. At 1.0 mg/ml concentration, EtOAc fraction showed absorbance of 1.72, be higher than Ascorbic acid. Cell viability was evaluated according to the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyl tetrazolium Bromide) assay. By MTT assay, all fractions showed a significant reduction in cell viability on COLO 205 (Human colon carcinoma cell) at the highest concentration tested (200㎍/ ㎖) with over 70% decrease in cell viability was obtained, and the highest significantly inhibiting effect occurred in butanol fraction with approximately 90% reduction in cell viability. Conclusion: We demonstrated that Mahonia Nepalensis stem extract has highly potential in anti-cancer activity. Further studies are necessary in order to explore the variety of Mahonia Nepalensis stem to be applied as a valuable natural material.
        43.
        2016.11 서비스 종료(열람 제한)
        매립지에서 발생하는 매립가스는 악취를 발생시켜 주변지역 대기환경을 저해하고 있다. 매립가스의 주성분은 온실가스인 이산화탄소(CO2)와 메탄가스(CH4)로 구성되어 있어, 바이오에너지와 같은 대체에너지 생산 기술 등의 연구에 활용되고 있다. 본 연구에서는 가스화 공정에서 발생하는 RDF char를 이용하여 CO2/CH4 개질 반응을 통해 생성되는 합성가스의 주성분인 CO, H2의 생성 특성에 대해 연구하였다. 1023∼1173K의 온도에서 CH4/CO2 ratio는 1.3으로 고정하여 혼합된 CO2와 CH4를 RDF char와 반응시켜 생성되는 H2와 CO의 변화를 측정하였다. 실험 결과에는 반응 온도가 1123K일 때 SUS bed의 CO2 전환율은 3.2%로 나타났으며, 반면 RDF char에서의 CO2 전환율은 81.7%로 나타났다. 이러한 실험결과로 RDF char는 CO2 개질반응에 촉매 역할을 하는 것으로 판단된다. 반응 후 RDF char 성분 분석 결과에 따라 함량이 높은 CaO는 반응전과 후 비슷한 결과를 나타났고 CO2 전환에 영향을 주지 않아 촉매 역할을 하는 Fe2O3나 TiO2에 의한 것으로 판단된다. 산소가 없는 경우에 RDF char에 의한 CO2와 CH4 개질 반응은 온도 증가에 따라 CO2 전환율은 45.3%(1023K)에서 83.16%(1173K)로 증가하였고 CH4 전환율은 10.2%(1023K)에서 27.0%(1173K)로 증가하였다. 또한 산소가 있는 경우는 산소 없는 경우보다 CH4 전환율은 1173K에서 27.0%에서 41.1%로 증가하고 발생가스의 H2 비율은 15.8%에서 22.3%로 증가한 것으로 나타났다. 이는 RDF char에 의해 메탄과 이산화탄소 개질 반응에 Reforming reaction과 Reverse WG shift reaction, Boudouard reaction, Reverse WG shift reaction에 의한 영향을 받는 것으로 판단된다.
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