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        검색결과 5

        1.
        2019.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Severe wall thinning is found on the tube of a low-pressure evaporator(LPEVA) module that is used for a heat recovery steam generator(HRSG) of a district heating system. Since wall thinning can lead to sudden failure or accidents that lead to shutdown of the operation, it is very important to investigate the main mechanism of the wall thinning. In this study, corrosion analysis associated with a typical flow-accelerated corrosion(FAC) is performed using the corroded tube connected to an upper header of the LPEVA. To investigate factors triggering the FAC, the morphology, composition, and phase of the corroded product of the tube are examined using optical microscopy, scanning electron microscopy combined with energy dispersive spectroscopy, and x-ray diffraction. The results show that the thinnest part of the tube is in the region where gas directly contacts, revealing the typical orange peel type of morphology frequently found in the FAC. The discovery of oxide scales containing phosphate indicates that phosphate corrosion is the main mechanism that weakens the stability of the protective magnetite film and the FAC accelerates the corrosion by generating the orange peel type of morphology.
        4,000원
        2.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Many kinds of medicinal herbs have been used to treat inflammation in Oriental medicine. However, there few studies have investigated the anti-inflammatory activity of medicinal herbs. In this study, we used mouse bone marrow cells (BMs) treated with lipopolysaccharide (LPS), a simulator of osteomyelitis, to screen medicinal herbs having anti-inflammatory activity. Specifically, we investigated the activity of an extract of Rhus chinensis (RC) using metabolic activity and cytokine production of the BMs treated with LPS and RC. The metabolic activity of BMs was measured using Cell Counting Kit-8® solution. RC decreased the metabolic activity of LPS-treated BMs. A viability assay using trypan blue solution demonstrated that RC marginally decreased the viability of LPS-treated BMs. Flow cytometry analysis revealed that RC decreased the mitochondrial membrane potential of BMs, regardless of LPS treatment. To investigate the anti-inflammatory activity of RC, we measured the production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 in BMs. LPS increased the production of both cytokines in BMs. Interestingly, RC induced a greater increase in IL-10 than TNF-alpha in LPS-treated BMs. Taken together, RC decreased metabolic activity and modulated the production of inflammation-related cytokines in LPS-treated BMs. These findings suggest that RC can be used as a medicinal herb with anti-inflammatory activity.
        4,000원
        3.
        2014.12 구독 인증기관 무료, 개인회원 유료
        Articles in one domestic journal, English Teaching (ET), and one international journal, TESOL Quarterly (TQ) from 2011 to 2013 were surveyed in order to analyze current research trends and to suggest better orientation toward future research focusing on participants, research methods, target language skills, and research topics. The results show that university students have participated most in both of the journal articles, indicating that they are practically available to the researchers in higher educational settings. The proportion of quantitative and qualitative research methods was well balanced in TQ, while, in ET, more than 50 percent of the articles relied on quantitative research methodology along with a relatively larger proportion of mixed method research in ET. In terms of target language skills, writing has been studied most in ET and speaking in TQ, showing growing interest in productive language skills nowadays. As for research topics, articles based on socio-cultural factors have been published most in TQ and articles based on classrooms pedagogy in ET, which reflects that English learning is performed mostly in classroom settings in Korea. Pedagogical implications and suggestions are made based on the findings
        4,500원
        4.
        2012.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study analyzed the text readability of the College Scholastic Ability Test (CSAT) and High School English Ⅱ textbooks by focusing on reading and compared the difficulty levels between them. To analyze the readability, the Flesh 2.0 for Windows and the Web VP 1.5 (2003) were used. To find out about high school students’ attitudes and behavior towards English and their preferences of English books, a questionnaire consisting of ten questions was administered. The results revealed that the textbooks are more readable than the CSATs in terms of the Flesch-Kincaid Reading Grade Level (RGL) and Reading Ease Score (RES). The average length per sentence of the textbooks is shorter than that of the CSATs. Furthermore, the CSATs have a higher percent of academic words than the textbooks. The questionnaire results showed that the participants, 228 second-year high school boy and girl students, preferred CSAT prep books, followed by EBS books and textbooks. Based on the findings, the basic directions of the CSAT and the guidelines to write textbooks have been suggested.
        6,100원