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        검색결과 5

        1.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Synergetic effect of multi-walled carbon nanotubes (MWCNTs)/nanoclays hybrid was investigated on the properties of highimpact polystyrene (HIPS) nanocomposite foams. The glass transition temperature and the cellular structure including the cell size and cell density were studied in details. Adding MWCNT and nanoclay increased the glass transition temperature of HIPS by 8.5 °C and 1.5 °C, respectively. The experimental results indicated that the cell size of HIPS foams was reduced from 84.05 to 60.97 μm and 40.22 μm using MWCNTs and nanoclays, respectively. The synergetic effect of MWCNT/nanoclay was more significant by reducing the cell size to 13.69 μm. The cell density was improved from 5.79 × 104 to 1.77 × 105 cell/ cm3 using MWCNTs and to 9.39 × 106 cell/cm3 using nanoclays. The cell density reached to 2.90 × 107 cell/cm3 using the synergetic effect of MWCNT/nanoclay.
        4,000원
        2.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A carbon fiber reinforced thermoplastic (CFRTP) was irradiated with a high energy electron-beam. As a result, the tensile strength of high-density polyethylene (HDPE)-based CFRTPs was significantly improved by gradually increasing the electron-beam dose. It was confirmed that the adhesion between CF and HDPE was improved and the surface properties of CF and HDPE were readily modified by electron-beam. It was verified from spectroscopic analysis that various oxygencontaining functional groups were formed on the surface of CF and HDPE by irradiation and we believe that strong attractive interactions took place among these functional groups at the interface of CFs and HDPE. Finally, it was conclusive that electron-beam irradiation provided two main effects on CFRTPs. One was cross-linking of thermoplastic resin for efficient load transfer from resin to CF and the other was formation of surface functional group and attractive interaction of these functional groups at the interface of fiber and matrix. These two effects showed synergetic contribution to enhance the mechanical properties of CFRTP.
        4,200원
        4.
        2016.07 구독 인증기관·개인회원 무료
        Businesses today are looking for new ways to acquire and retain customers, by delivering innovative products and services, which serve each customer's individual demands. Fo- cusing on individual customer needs and addressing each request individually with a ser- vice or product that is perceived as being customized has become the focal point of Inter- action Orientation (IO), a firm-level strategic orientation developed by Ramani and Kumar (2008). Entrepreneurial Orientation (EO) is also a firm-level strategic construct, which reflects the "processes, practices, and decision-making activities" that firms use to identify and exploit new business opportunities (Lumpkin & Dess, 1996, p.136). As op- posed to IO, EO is a well-established concept, being one of the most examined topics in entrepreneurship research. However, most studies have focused on cross-sectional de- signs to assess the relationship to firm performance, leading to numerous research calls focusing on the need for more dynamic investigations (Saeed, Yousafzai, & Engelen, 2014). Based on our analysis including 247 S&P500 firms from a variety of industries over a period of three years, this longitudinal study is one of the first to assess the short-term and long-term effects of IO and EO. To establish the firm's levels of IO and EO, we ana- lyze the content of Letters to Shareholders (LtS), as LtS have been widely used to assess different strategic orientations - Market Orientation, Learning Orientation - including EO (Noble et al., 2002; Short, Broberg, Cogliser, & Brigham, 2010; Zachary, McKenny, Short, & Payne, 2011). We relied on multisource secondary data for performance indica- tors and included several control variables: past performance of the firm, firm age, firm size, as well as industry specific effects. Our results confirm that each orientation has a positive impact on the firm's financial suc- cess in the long-term but a combined IO-EO strategy reveals a negative effect on firm performance in the long-term. This study investigates the synergies between IO and EO in a longitudinal setting and using objective financial performance indicators, establish- ing the advantages and disadvantages of implementing a single or combined strategy.
        5.
        2012.06 구독 인증기관·개인회원 무료
        MAC-T cells, bovine mammary epithelial cell line, have been utilized to investigate bovine lactation system. A lactogenic phenotype of the cell is generally induced by combination of dexamethasone, insulin and prolactin (PRL). Effect of vitamin A derivative retinoic acid (RA), well reported as an inducer for differentiation in many cells, to MAC-T cell has not been studied. The objective of this study was to confirm effect of differentiation potential by RA treatment in MAC-T cells and to test effect of combination of RA and PRL treatment. In RA or PRL treatment groups, both has induced morphological change to secrete milk of MAC-T cells. Combination of RA and PRL treatment group has presented noticeable lactogenic phenotype among the all group. This phenotype observed at four days after treatment and showed critical morphological change that was rouphly spherical structure at eight days. RA alone treatment showed slightly inhibition of proliferation in the MAC-T cells, but co-treatment with PRL was improved the cell growth more than control group. MTT assay result and Bcl-xL/Bax ratio of mRNA abundance also was entirely consistent with earlier one. RA-induced differentiation of MAC-T cells has increased αs1-casein, αs2-casein and β-casein mRNA expression compared to PRL treatment group. Expression of αs1-casein, αs2-casein and β-casein genes represented the maximum value in the combination of RA and PRL treatment group at four days. The value of each casein gene expression was 4-, 5.5- and 5.9-fold, respectively, as compared with PRL alone treatment in the MAC-T cells. Protein level of β-casein releasing to the medium also induced the highest level at four days. These results provide evidence that RA can induce the differentiation of MAC-T cells and have synergetic effect with PRL.