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        검색결과 380

        63.
        2021.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This research aims to study the simultaneous extraction and transesterification of Chlorella vulgaris (C. vulgaris) using microwave irradiation with methanol as solvent and potassium hydroxide (KOH) as catalyst. The microwave-assisted insitu transesterification of C. vulgaris is assessed at various ratios of biomass-to-methanol, reaction times, and catalyst concentrations during the centrifugation and evaporation process. Gas chromatography-mass spectrometry (GC-MS) analysis is performed to confirm fatty acid methyl ester (FAME) composition. Biodiesel preparation is carried out by simultaneous extraction and transesterification of microalgae from C. vulgaris. The product is then characterized using Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR); microalgae are observed using scanning electron microscopy (SEM). The highest amount of FAME is obtained at a biomass-to-methanol ratio of 1:12, reaction time of 40 min, and catalyst concentration of 2 wt%. Biodiesel shows conversion to about 77.64% of methyl ester (methyl myristate, methyl palmitoleate, methyl linoleate, methyl oleate, methyl arachidonate, and methyl 5,8,11,14,17-eicosapentanoate).
        4,000원
        64.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        우파니샤드는 서양철학과 미학의 전통에서 지식의 내용을 형성하는데 지대한 영향을 끼친 철학적 논쟁의 기본 텍스트가 된다. 예이츠는 세상은 변화무쌍한 환영이라서 신과 우주의 직물위에서 춤추다는 사실을 이해할 수 있어서 우파니샤드철 학을 포괄적으로 수용하는 아일랜드, 영국, 유럽 배경의 시인이다. 이런 관점의 수용은 곧 예이츠로 하여금 표피적인 세상의 번잡함에서 벗어나 영원성에 도달하기에 이른다.
        7,700원
        69.
        2021.03 구독 인증기관 무료, 개인회원 유료
        Dental health care workers (DHCW) are at a risk of occupational exposure to Helicobacter pylori from the aerosolized oral biofilms and saliva of patients. We designed this study to investigate the prevalence of H. pylori in the oral biofilms of a group of dental and non-dental undergraduates from Sri Lanka. After obtaining informed consent, oral biofilms were collected from 38 dental undergraduates (19 males and 19 females) undergoing clinical training and 33 non-dental undergraduates (14 males and 19 females). The participants were in the age range of 22–27 years and had healthy periodontium. Total DNA from the oral biofilms were extracted, and H. pylori DNA was detected using polymerase chain reaction (PCR) amplification of 16S rRNA gene of H. pylori using JW22-JW23 primers, and the results were confirmed using PCR amplification of H. pylori -urease specific HPU1-HPU2 primers. Out of 71 participants, 11 (28.95%) dental and 3 (9.09%) non-dental undergraduates had H. pylori in their oral biofilms indicating an overall prevalence rate of 19.72% (14/71). Thus, the prevalence of H. pylori in oral biofilms was significantly higher in dental undergraduates than in non-dental undergraduates (p < 0.05). An odds ratio of 4.07 indicated that dental undergraduates were four times more likely to harbor H. pylori in their oral biofilms than nondental undergraduates. Foregoing data support the fact that there may be greater occupational risk of exposure to H. pylori for dental undergraduates during clinical training than that for non-dental undergraduates, warranting meticulous infection control practices during clinical dentistry.
        4,000원
        70.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study was conducted in a goat farm for pregnancy diagnosis by using vaginal cytology and B-mode real time ultrasound using 5 MHz probe by transabdominal method. Seventeen pregnant does were used for this study. The objective of the study was to determine the earliest day of pregnancy and describe the chronological characteristics of pregnancy from day 22 to day 40 for vaginal cytology and day 25 to day 60 for ultrasonography of gestation. The differences among the average percentage of cell value in different age of pregnancy were significant (p < 0.05). The average percentage of intermediate cells (81.12%) was also significantly (p < 0.05) higher than superficial (9.41%), keratinized (7.10%) and neutrophil (2.61%) on 22-40th days of pregnancy. In case of real time B-mode ultrasonography, the gestational sac was observed only in three does out of seventeen (17.6 %) at 25-30 days whereas the placentomes and heart beat of the foetus were first detected at 31-35 days in six does (35.3%). The foetal leg buds were first visualized at 36-40 days in four does (23.5%) whereas the foetal vertebral column was first observed at 36-40 days of gestation in only three does (17.6%). In conclusion, vaginal cytology and trans-abdominal ultrasonography can be used for detection of early pregnancy in does.
        4,000원
        71.
        2020.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the discovery of a giant exoplanet in the microlensing event OGLE-2017-BLG-1049, with a planet―host star mass ratio of q = 9.53 ± 0.39 × 10-3 and a caustic crossing feature in Korea Microlensing Telescope Network (KMTNet) observations. The caustic crossing feature yields an angular Einstein radius of θE = 0.52 ± 0.11 mas. However, the microlens parallax is not measured because the time scale of the event, tE ≃ 29 days, is too short. Thus, we perform a Bayesian analysis to estimate physical quantities of the lens system. We fi nd that the lens system has a star with mass Mh = 0.55+0.36 -0.29 M⊙ hosting a giant planet with Mp = 5.53+3.62 -2.87 MJup, at a distance of DL = 5.67+1.11 -1.52 kpc. The projected star{planet separation is aㅗ = 3.92+1.10 -1.32 au. This means that the planet is located beyond the snow line of the host. The relative lens{source proper motion is μrel ~ 7 mas yr-1, thus the lens and source will be separated from each other within 10 years. After this, it will be possible to measure the flux of the host star with 30 meter class telescopes and to determine its mass.
        4,000원
        72.
        2020.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A combination of Polycarbonate (PC) material and Polymethylmethacrylate (PMMA), fabricated using an injection molding machine, has been investigated to determine its advantages, as studied in Ref. 1). This paper aims to investigate the optimization of PMMA/PC blend for both tensile yield strength and impact strength. Furthermore, interaction effects of process conditions on mechanical properties including tensile yield strength and impact strength of PMMA/PC blend by injection molding process are interpreted in this study. Tensile and impact specimens are designed following ASTM, type V, and are fabricated by injection molding process. The processing conditions such as melt temperature, mold temperature, packing pressure, and cooling time are applied; each factor has three levels. As a result, in comparison with optimization of separated responses, mechanical properties of PMMA/PC are found to decrease when optimizing both tensile and impact strengths simultaneously. The melt temperature is found to be the most significant interaction parameter with the mold temperature and packing pressure. In addition, there is more interaction between the mold temperature and cooling time. This investigation provides a useful understanding of the control of injection molding processing of polymer blends in optical application.
        4,000원
        73.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated the cytotoxic potential of three different commercially available absorbent feminine hygiene products and one transdermal patch using direct contact and extract exposure methods. Two different cell lines were used – mouse fibroblast L929 and normal human skin fibroblast CCD-986sk cell lines. The test samples were extracted using three different methods in accordance to International Organization for Standardization (ISO). Viability of cells was analyzed using MTT assay and morphology of the cells were also observed using phase contrast microscopy. Overall, the direct contact method using L929 cells showed that all the test samples had no toxic effect when exposed to extracts for 1 h. For the exposure method, no toxic effect was observed in both L929 and CCD986sk cells incubated with all the test samples regardless of the extraction methods used.
        4,000원
        74.
        2020.11 구독 인증기관 무료, 개인회원 유료
        The purpose of this paper is to provide a critical overview of the use of social marketing in Asia. A total of 17 countries were included in this paper. We demonstrate the development and trends of social marketing in Asia by highlighting prominent and effective cases. Our findings reveal that social marketing practice represents a wide spectrum of topics. However, public policy and education outweigh adoption of social marketing to address social issues. Several barriers influence adoption and effectiveness of social marketing. We highlight a few and recommend strategies to overcome them.
        4,000원
        76.
        2020.11 구독 인증기관 무료, 개인회원 유료
        This research aimed to investigate the impacting psychological factors for Vietnamese’s intention to stop littering. A quantitative method using self-reported online questionnaire was adopted to collect data from Vietnamese residents and Partial Least Squares Structural Equation Modelling (PLS-SEM) method was employed to examine the proposed relationships. The results indicate that higher connectedness to nature and lower perceived behavioral control are associated with higher intention to stop littering in Vietnam. Limitations of current study and future research directions are outlined.
        4,000원
        77.
        2020.11 구독 인증기관 무료, 개인회원 유료
        This paper describes a study that 1) explores ageing consumers’ perceptions of functionally beneficial but simple technology, and 2) tests how readily ageing consumers accept such technology. A mixed method approach is proposed to introduce ageing consumers to Google Home, to firstly demonstrate and highlight selected functional benefits associated with safety, connection with others and community, and entertainment; secondly determine ageing consumer attitudes toward that; and thirdly to test trial and adoption. Results will provide much needed insights into how emerging but relatively commonplace technology can be better integrated into ageing consumer groups to enhance wellbeing, increase independence and reduce isolation.
        4,000원
        78.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Graphene nanoribbons materialize as a next-generation carrier for development of nanodimensional diagnostic devices and drug delivery systems due to the unique and cutting-edge electronic, thermal, mechanical and optical properties associated with graphene. This review article focuses on the important applications of GNRs in the field of biomedicine and biosensing. Graphene nanoribbons are highly developed form of graphene with a wide importance due to their distinctive properties such as large surface area, enhanced mechanical strength and improved electro-conductivity. GNRs are effective substitutes for conventional silicon-based transistors used in biochemical reactions and exploited in the fields of biomedicine and diagnostics due to their effective uptake by mammalian cells. The cellular interactions of GNRs consist of highly specific receptormediated transport, phagocytosis and non-specific transport systems involving copious forces of adhesion. The presence of quantum chains in GNRs increases their potential for fabrication of technically challenging sensing devices in the future.
        4,200원
        79.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Facile process for the fabrication of multi-layer graphene thin film (MLGF) is reported here. Multi-layer graphene dispersion prepared by liquid-phase exfoliation of graphite was sprayed on a glass substrate by spray pyrolysis method. The structural, optical and electrical properties of the deposited MLGF are investigated. The sheets of graphene are deposited uniformly on the substrate and distribution of small graphene sheets with size of 300–500 nm can be observed in SEM image. AFM and micro-Raman results ensured that the spray-coated graphene thin film is composed of multi-layer graphene sheets. Spray coated graphene thin film showed significant optical transparency of 57% in the visible region (400–550 nm). MLGF possessed the electrical conductivity in the order of 744 S/m with surface resistivity of 3.54 k Ω/sq. The prepared liquid-phase exfoliated graphene thin film showed superior photoelectric response. The results of this study provided a framework for fabricating an optimized MLGF using a spray pyrolysis route for optoelectronics devices.
        4,000원
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