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        검색결과 220

        124.
        2003.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The basic objective of helioseismology is to determine the structure and the dynamics of the Sun by analysing the frequency spectrum of the solar oscillations. Accurate frequency measurements provide information that enables us to probe the solar interior structure and the dynamics. Therefore the frequency of the solar oscillation is the most fundamental and important information to be extracted from the solar oscillation observation. This is why many efforts have been put into the development of accurate data analysis techniques, as well as observational efforts. To test one's data analysis method, a realistic artificial data set is essential because the newly suggested method is calibrated with a set of artificial data with predetermined parameters. Therefore, unless test data sets reflect the real solar oscillation data correctly, such a calibration is likely incomplete and a unwanted systematic bias may result in. Unfortunately, however, commonly used artificial data generation algorithms insufficiently accommodate physical properties of the stochastic excitation mechanism. One of reason for this is that it is computaionally very expensive to solve the governing equation directly. In this paper we discuss the nature of solar oscillation excitation and suggest an efficient algorithm to generate the artificial solar oscillation data. We also briefly discuss how the results of this work can be applied in the future studies.
        4,000원
        128.
        2003.04 구독 인증기관·개인회원 무료
        132.
        1998.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        V. cholerae non-O1 49균주와 V. cholerae O1, V. mimicus, V. vulnificus와 V. parahaemolyticus의 균체지방산(fatty acid methyl ester; FAME)을 gas liquid chromatogrphy로 분석하였다. 이들 분석자료를 통계학적으로 처리하여 Vibrio 종과 V. cholerae의 혈청형별 유연성을 비교 검토하였다. 검출된 지방산은 모두 41종이었고 분포량이 많은 것은 16:0, 16:1 cis 9, 18:1 trans 9/16/cis 11과 15:0 iso 2 OH/16:1 cis 9 였다. 검출된 지방산 중에서도 35종은 V. cholerae를 동정하는데 주요한 인자로 작용되었다. 지방산분포를 UPGMA(비가중수리분석)으로 dendrogram을 작성한 결과 V. cholerae non-O1은 V cholerae O1보다 V mimieus가 더 높은 유사도를 나타내었다. 특히 hydoxy acid는 V. chozerae의 아종단위를 동정하는데 중요하였다. V. choEeore non-O1중에서 O2, O5, O8, O10, O14, O27, O37, O39, O45와 O69의 총 10 종류 혈청형을 대상으로 지방산 조성에 의 한 유사성을 검토한 결과 유사도가 92% 이상 수준에서 7개의 아종를 형성하여 혈청형과 지방산 조성간에는 유의할 만한 상관관계가 있었다. 따라서 V. cholerne non-O1의 동정 및 역학적인 조사시 지방산 분석은 유용하게 활용될 수 있음을 알 수 있었다.
        4,000원
        133.
        1996.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        4,800원
        136.
        1995.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        한국산 환성충상과의를 연구하는 중 Criconemeatidae과에 속하는 Criconema longulum, C. orientale, C. psammophilum 등 한국 3 미기록종이 발견되었고, Discocriconemella hengsungica, Hemicriconemoides brachyurus, H. mangiferae, H. varionadus 및 Xenocriconemella macrodora 등 5 기지종에 대한 형태적인 검토, 기주식물 및 분포지역을 발표한다.
        4,000원
        137.
        2021.03 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        Utilizing a new version of the sunspot number and group sunspot number dataset available since 2015, we have statistically studied the relationship between solar activity parameters describing solar cycles and the slope of the linear relationship between the monthly sunspot numbers and the monthly number of active days in percentage (AD). As an effort of evaluating possibilities in use of the number of active days to predict solar activity, it is worthwhile to revisit and extend the analysis performed earlier. In calculating the Pearson’s linear correlation coefficient r, the Spearman’s rank-order correlation coefficient rs, and the Kendall’s τ coefficient with the rejection probability, we have calculated the slope for a given solar cycle in three different ways, namely, by counting the spotless day that occurred during the ascending phase and the descending phase of the solar cycle separately, and during the period corresponding to solar minimum ± 2 years as well. We have found that the maximum solar sunspot number of a given solar cycle and the duration of the ascending phase are hardly correlated with the slope of a linear function of the monthly sunspot numbers and AD. On the other hand, the duration of a solar cycle is found to be marginally correlated with the slope with the rejection probabilities less than a couple of percent. We have also attempted to compare the relation of the monthly sunspot numbers with AD for the even and odd solar cycles. It is inconclusive, however, that the slopes of the linear relationship between the monthly group numbers and AD are subject to the even and odd solar cycles.
        138.
        2020.12 KCI 등재 서비스 종료(열람 제한)
        Chronological aging and photoaging affect appearance, causing wrinkles, pigmentation, texture changes, and loss of elasticity in the skin. Phragmites communis is a tall perennial herb used for its high nutritional value and for medicinal purposes, such as relief from fever and vomiting and facilitation of diuresis. In this study, we investigated the effects of ethanol extract of P. communis rhizome (PCE) on skin aging. The total flavonoid and total phenolic content in PCE were 2.92 ± 0.007 ㎍ of quercetin equivalents (QE) and 231.8 ± 0.001 ㎍ of gallic acid equivalents (GAE) per 100 ㎎ of dried extract (n = 3). The half-maximal inhibitory concentration (IC50) values of PCE for 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and hydrogen peroxide scavenging activities were 0.96 and 0.97 ㎎/mL, respectively. PCE showed inhibitory effects on tyrosinase when L-tyrosine (IC50 = 1.25 ㎎/mL) and L-3,4-dihydroxyphenylalanine (IC50 = 0.92 ㎎/mL) were used as substrates. PCE treatment up to 200 ㎍/mL for 24 h did not cause any significant cytotoxicity in B16F10 melanocytes, human dermal fibroblasts (HDFs), and HaCaT keratinocytes. In B16F10 melanocytes, PCE (25 and 50 ㎍ /mL) inhibited melanin production and cellular tyrosinase activity after challenge with α-melanocyte-stimulating hormone (α-MSH; p < 0.05). In HDFs, PCE suppressed the mRNA expression of matrix metalloproteinase-1 (MMP-1) and reduced the activity of elastase (p < 0.05). In addition, ultraviolet B (UVB)-mediated downregulation of hyaluronic acid synthase-2 gene expression in HaCaT keratinocytes was also effectively suppressed by PCE treatment. Overall, our results showed that PCE has potential anti-skin aging activity associated with the suppression of hyperpigmentation, wrinkle formation, and reduction in dryness. PCE is a promising candidate for the development of an anti-skin aging cosmetic ingredient.
        139.
        2020.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The purpose of this study is to investigate whether the ECFA impacted the efficiency of banks in China and Taiwan from 2008 to 2017. This study follows Seiford and Zhu (2002), who recommend using the standard data envelopment analysis model to measure performance by increasing the desirable outputs and decreasing the undesirables. The finding was that overall technical efficiency increased from 2012 to 2017, reaching 0.575, 0.652, 0617, 0.689, 0.701 and 0.74, respectively. This result implies bank efficiency did indeed improve after China and Taiwan signed the ECFA cooperation agreement. The study found that the mean technical efficiency was 0.8756 in China, greater than Taiwan’s mean of 0.3511, implying that Chinese banks experienced a greater increase in efficiency after signing the EFCA. One possible reason explored in this study is that China’s economy is currently growing at the highest rate in the world, and the banks’ efficiency has benefited from greater economic growth. This suggests that cross-strait sustained negotiations to consummate an agreement on trade in the services will be a very important mission in the future. This result also provides significant evidence suggesting that not accounting for undesirable output while estimating the evolution of the model may seriously distort efficiency results.
        140.
        2019.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        We explore the associations between the total sunspot area, solar north-south asymmetry, and Southern Oscillation Index and the physical characteristics of clouds by calculating normalized cross-correlations, motivated by the idea that the galactic cosmic ray influx modulated by solar activity may cause changes in cloud coverage, and in turn the Earth’s climate. Unlike previous studies based on the relative difference, we have employed cloud data as a whole time-series without detrending. We found that the coverage of high-level and low-level cloud is at a maximum when the solar north-south asymmetry is close to the minimum, and one or two years after the solar north-south asymmetry is at a maximum, respectively. The global surface air temperature is at a maximum five years after the solar north-south asymmetry is at a maximum, and the optical depth is at a minimum when the solar north-south asymmetry is at a maximum. We also found that during the descending period of solar activity, the coverage of low-level cloud is at a maximum, and global surface air temperature and cloud optical depth are at a minimum, and that the total column water vapor is at a maximum one or two years after the solar maximum.