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김현모,김호준,공창숙,이봉호,심현보,서영완 한국해양과학기술원 2021 Ocean and Polar Research Vol.43 No.3
In the present study, the halophyte C. falcatum extract and its solvent fractions (n-hexane, 85% aqueous methanol, n-butanol, and water) were evaluated for antioxidant and anti-inflammatory activities. Antioxidative ability was measured by DPPH radical, intracellular reactive oxygen species (ROS) and peroxynitrite scavenging, DNA oxidation inhibition, and ferric reducing antioxidant power (FRAP). For DPPH radical and peroxynitrite scavenging, DNA oxidation inhibition, and FRAP, 85% aq.MeOH and n-BuOH fractions showed significant scavenging activity. For production of intracellular ROS in HT-1080 cells, 85% aq.MeOH fraction showed the highest scavenging activity. In addition, anti-inflammatory activity was also assessed by measuring the inhibitory effect against mRNA expression of pro-inflammatory factors (NO, IL-1β, IL-6 and COX-2) in LPS-stimulated Raw 264.7 macrophages. For NO production, crude extract exhibited a strong inhibitory effect at a concentration of 100 μg/ml. For mRNA expression of pro-inflammatory cytokines (IL-1β, IL-6, and COX-2), n-BuOH greatly suppressed expression levels of IL-1β and IL-6 at 100 μg/ml concentration while 85% aq. MeOH fraction significantly inhibited that of COX-2 even at 100 μg/ml. These results suggest that C. falcatum may be used as a potential source for the development of a natural antioxidant or anti-inflammatory agent.
김현모,박재홍 한국경영정보학회 2016 Asia Pacific Journal of Information Systems Vol.26 No.4
This research aims to examine the predictive power of multiple online stock message boards, namely, NAVER Finance and PAXNET, which are the most popular stock message boards in South Korea, in stock market activities. If predictive power exists, we then compare the predictive power of multiple online stock message boards. To accomplish the research purpose, we constructed a panel data set with close price, volatility, Spell out acronyms at first mention.PER, and number of posts in 40 companies in three months, and conducted a panel vector auto-regression analysis. The analysis results showed that the number of posts could predict stock market activities. In NAVER Finance, previous number of posts positively influenced volatility on the day. In PAXNET, previous number of posts positively influenced close price, volatility, and PER on the day. Second, we confirmed a difference in the prediction power for stock market activities between multiple online stock message boards. This research is limited by the fact that it only considered 40 companies and three stock market activities. Nevertheless, we found correlation between online stock message board and stock market activities and provided practical implications. We suggest that investors need to focus on specific online message boards to find interesting stock market activities.
온라인 주식게시판 정보와 주식시장 활동에 관한 상관관계 연구
김현모,운호영,소리,박재홍 한국경영정보학회 2014 Asia Pacific Journal of Information Systems Vol.24 No.4
Individual investors are increasingly flocking to message boards to seek, clarify, and exchange information. Businesses like Seekingalpha.com and business magazines like Fortune are evaluating, synthesizing, and reporting the comments made on message boards or blogs. In March of 2012, Yahoo! Finance Message Boards recorded 45 million unique visitors per month followed by AOL Money and Finance (19.8 million), and Google Finance (1.6 million) [McIntyre, 2012]. Previous studies in the finance literature suggest that online communities often provide more accurate information than analyst forecasts [Bagnoli et al., 1999; Clarkson et al., 2006]. Some studies empirically show that the volume of posts in online communities have a positive relationship with market activities (e.g., trading volumes) [Antweiler and Frank, 2004; Bagnoli et al., 1999; Das and Chen, 2007; Tumarkin and Whitelaw, 2001]. The findings indicate that information in online communities does impact investors’ investment decisions and trading behaviors. However, research explicating the correlation between information on online communities and stock market activities (e.g., trading volume) is still evolving. Thus, it is important to ask whether a volume of posts on online communities influences trading volumes and whether trading volumes also influence these communities. Online stock message boards offer two different types of information, which can be explained using an economic and a psychological perspective. From a purely economic perspective, one would expect that stock message boards would have a beneficial effect, since they provide timely information at a much lower cost [Bagnoli et al., 1999; Clarkson et al., 2006; Birchler and Butler, 2007]. This indicates that information in stock message boards may provide valuable information investors can use to predict stock market activities and thus may use to make better investment decisions. On the other hand, psychological studies have shown that stock message boards may not necessarily make investors more informed. The related literature argues that confirmation bias causes investors to seek other investors with the same opinions on these stock message boards [Chen and Gu, 2009; Park et al., 2013]. For example, investors may want to share their painful investment experiences with others on stock message boards and are relieved to find they are not alone. In this case, the information on these stock message boards mainly reflects past experience or past information and not valuable and predictable information for market activities. This study thus investigates the two roles of stock message boards–providing valuable information to make future investment decisions or sharing past experiences that reflect mainly investors’ painful or boastful stories. If stock message boards do provide valuable information for stock investment decisions, then investors will use this information and thereby influence stock market activities (e.g., trading volume). On the contrary, if investors made investment decisions and visit stock message boards later, they will mainly share their past experiences with others. In this case, past activities in the stock market will influence the stock message boards. These arguments indicate that there is a correlation between information posted on stock message boards and stock market activities. The previous literature has examined the impact of stock sentiments or the number of posts on stock market activities (e.g., trading volume, volatility, stock prices). However, the studies related to stock sentiments found it difficult to obtain significant results. It is not easy to identify useful information among the millions of posts, many of which can be just noise. As a result, the overall sentiments of stock message boards often carry little information for future stock movements [Das and Chen, 2001; Antweiler and Frank, 2004]. This study notes that as a dependent variable, trading ...