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        검색결과 9,512

        3701.
        2016.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present the results of BV time-series photometry of the globular cluster NGC 288. Ob- servations were carried out to search for variable stars using the Korea Microlensing Telescope Network (KMTNet) 1.6-m telescopes and a 4k pre-science CCD camera during a test observation from August to December, 2014. We found a new SX Phe star and confirmed twelve previously known variable stars in NGC 288. For the semi-regular variable star V1, we newly determined a period of 37.3 days from light curves spanning 137 days. The light-curve solution of the eclipsing binary V10 indicates that the system is probably a detached system. The pulsation properties of nine SX Phe stars were examined by applying multiple frequency analysis to their light curves. We derived a new Period-Luminosity (P-L) relation, hMV i = −2.476(±0.300) logP − 0.354(±0.385), from six SX Phe stars showing the fundamental mode. Additionally, the period ratios of three SX Phe stars that probably have a double-radial mode were investigated; PFO/PF = 0.779 for V5, PTO/PFO = 0.685 for V9, PSO/PFO = 0.811 for V11. This paper is the first contribution in a series assessing the detections and properties of variable stars in six southern globular clusters with the KMTNet system.
        4,300원
        3702.
        2016.12 구독 인증기관 무료, 개인회원 유료
        This study was undertaken to achieve a high bleaching efficacy with plasma, through longer application and reparative bleaching processes, by different shade evaluation methods. Extracted human teeth were divided into 6 groups (n=10). All teeth were treated in pairs. Low concentration of 15% carbamide peroxide (CP) was applied, with and without plasma, for 10, 20, and 30-min tooth bleaching, respectively. The bleaching procedure was repeated once daily for four days. The teeth were maintained in a moist environment provided by artificial saliva. The Vitapan Classical shade guide and Commission Internationale de L’Eclairage (CIELAB) color system were collectively used to measure the bleaching efficacy. Color evaluation was statistically analyzed using Student t-test and one-way analysis of variance (ANOVA) complemented by Tukey’s test. Combining the plasma with 15% CP showed significantly greater color changes compared to bleaching without plasma (p<0.05). A high bleaching efficacy with plasma is proportional to the repetitive application and the treatment time. A 30-min application with plasma provided the best bleaching. Repetitive bleaching showed lower probability of color relapse of the bleached tooth. The color change by shade guide correlated with the changes in CIELAB color system. A value of 1 color change units (CCU) conversion factor for overall color change (ΔE) values comparisons was 3.724 values. The two measuring methods provide a more accurate correspondence of color change. The repetitive and longer application for tooth bleaching, combined with plasma, has a strong bleaching effect and produces whiter teeth.
        4,000원
        3703.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mesenchymal stem cells (MSCs) are primary candidates for cell therapy and tissue engineering applications. A two-dimensional (2D) culture system is typically used for cell growth, but that method affects the characteristics of stem cells. The physiological cell environment connects cells not only to each other, but also to the extracellular matrix providing mechanical support, exposing the entire cell surface, and opening signaling pathways. The hanging drop method is the most widely used 3D culture method for spheroid formation. In this study, we investigated the relationship between spheroid size and changes in gene expression to determine the optimum spheroid size for use in tissue engineering. The expression levels of stemness factors such as NANOG, OCT4, and SOX2, angiogenic factors such as VEGF and IL-8, and osteogenic factors such as COX2 and TGF-β1 increased with spheroid size in the respective spheroid formation groups unlike the responses in their monolayer groups. Therefore, our results indicate that spheroid formation through the hanging drop method can increase the efficiency of MSCs-based tissue engineering over that obtained via traditional 2D cell culture systems.
        4,000원
        3704.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mesenchymal stem cells (MSCs) have been researched for use in biomedical applications, particularly for cell-based therapies and regenerative medicine due to their self-renewing capacity and ability to differentiate into multiple cell types such as adipose, bone, and tendon tissues. Cryopreservation of MSCs is a common preservation method that is advantageous for cellular therapies in human and veterinary medicine. Adipose tissue-derived cells have been shown to maintain their properties after cryopreservation. In this study, we investigated the morphology, proliferation (cumulative population doubling level and doubling time), cell surface markers (CD34, CD90, and CD105), and ability to differentiate into adipose, bone, and cartilage tissues in vitro of equine adipose tissue-derived MSCs (eAD-MSCs) and miniature pig adipose tissue-derived MSCs (mpAD-MSCs) with and without long-term cryopreservation. The eAD-MSCs and mpAD-MSCs were analyzed immediately and after being frozen in liquid nitrogen for 3 years and 2 years, respectively. Cryopreserved eAD-MSCs maintained their morphology, proliferation rate, and cell surface markers compared with fresh cells. With the exception of proliferation rate, cryopreserved mpAD-MSCs also maintained their fresh cell characteristics. The proliferation rate of cryopreserved mpAD-MSCs was higher than that for fresh cells. Cryopreservation did not change the adipogenic, chondrogenic, or osteogenic differentiation potentials of eAD-MSCs and mpAD-MSCs. In summary, long-term cryopreservation maintains the cell phenotype and differentiation ability of eAD-MSCs and mpAD-MSCs. These results might be useful when developing veterinary medicine and clinical applications.
        4,000원
        3705.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Earthworms, especially Eisenia andrei, are cultivated for a variety of purposes including waste disposal and compost production. In this study, bacteria from earthworm gut were cultured and the dominant species identified. Subsequently, we isolated bacteriophages able to lyse the isolated gut bacteria. Two dominant genera of gut bacteria, Aeromonas sp. and Citrobacter sp. were identified by using MALDI-TOF MS analysis and a library was constructed to find lytic phages. Phage EF1 showed lytic activity for C. freundii and two Citrobacter isolates, C. braakii and C. murliniae. These 3 species have similar sensitivities to EF1. Several aspects of the life cycle of EF1 were investigated by using C. freundii under optimal growth conditions. EF1 infects C. freundii with a moderate latent period, approximately 25 min, and a large burst size averaging 5 × 109 per infected cell. Moreover, the antimicrobial activity of EF1 was well maintained under diverse conditions including a broad temperature range of 40°C to 50°C and a wide pH range of 4 to 11. In conclusion, the results indicate that earthworm casting contain a wide range of bacteria species, for which there are various corresponding bacteriophages.
        4,000원
        3706.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Prion diseases are a class of transmissible fatal disorders. In order to identify alterations associated with the pathogenesis of prion diseases, several studies have been conducted involving differential gene expression analysis using cDNA libraries, mRNA differential displays, and gene microarrays. These genomic approaches may be useful for identifying genes that are differentially expressed in prion diseases and that may participate directly or indirectly in the pathogenesis of the disease. In this study, we compared the gene expression profiles of normal and CWD-infected TgElk mice using the GeneFishing differentially expressed gene (DEG) screening system and real-time PCR analysis. DEGs were screened using the ACP-based PCR method with GeneFishing synthesis. In order to validate candidate genes, we used quantitative PCR (qPCR), and eleven DEGs were identified. Five of these eleven DEGs were upregulated and two were downregulated in the CWD mice. The DEGs newly identified in this study may be useful for diagnosing and studying the pathogenesis of prion diseases.
        4,000원
        3707.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        4,000원
        3708.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Previous research developed lists of the most frequently used phrasal verbs in native English corpora. This study aims to discover how these high frequency phrasal verbs were presented in high school English textbooks in Korea. A high school English textbook corpus comprising 189,203 words taken from the listening scripts and reading passages of eight different textbook series was developed for the study. A corpus-based analysis of phrasal verbs revealed that each textbook series covered only 30% of most commonly used phrasal verbs in native corpora. In addition, the phrasal verbs used in the different textbook series rarely overlapped, suggesting a lack of systematic selection process. Among the recursive phrasal verbs appearing in the textbook series, high frequency phrasal verbs were more likely to be recursive and evenly distributed. A comparative analysis conducted with a referential corpus revealed that the textbooks employed fewer phrasal verbs than their comparative counterparts. In terms of meaning, 91% of high frequency phrasal verbs in the textbooks delivered their most frequent meanings while the rest 9% did not. The results of this study support the necessity of pedagogical guidelines for phrasal verbs.
        7,700원
        3709.
        2016.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study compared aural and written modes of presentation for the two item types, to explore the effects of question/option presentation mode and item type on EFL learners’ listening comprehension performance and their perception. One hundred and fifteen Korean college students who were divided into three different proficiency groups participated in the study. The participants took a listening test which consisted of dialogue-completion and Q&A multiple-choice items in the aural and written modes, followed by a survey on their perceptions, and a stimulated recall interview. The results showed that the least proficient group was more critically affected by the mode than the other two groups. The least proficient group performed significantly better in the written mode than in the aural mode, while they received similar scores on the two item types. The major factors that caused the discrepancy among the groups were memory capacity in the aural mode and reading ability in the written mode. The implications and suggestions on listening test development are discussed.
        6,700원
        3710.
        2016.12 구독 인증기관 무료, 개인회원 유료
        Many maritime accidents have been caused by human-error including such things as inadequate watch keeping and/or mistakes in ship handling. Also, new navigational equipment has been developed using Information Technology (IT) technology to provide various kinds of information for safe navigation. Despite these efforts, the reduction of maritime accidents has not occurred to the degree expected because, navigational equipment provides too much information, and this information is not well organized, such that users feel it to be complicated rather than helpful. In this point of view, the method of representation of navigational information is more important than the quantity of that information and research is required on the representation of information to make that information more easily understood and to allow decisions to be made correctly and promptly. In this paper, we adopt Augmented Reality (AR) technologies for the representation of information. AR is a 3D computer graphics technology that blends virtual reality and the real world. Recently, this technology has been widely applied in our daily lives because it can provide information more effectively to users. Therefore, we propose a new concept, a navigational system based on AR technology; we review experimental results from a ship-handling simulator and from an open sea test to verify the efficiency of the proposed system.
        4,200원
        3711.
        2016.12 구독 인증기관 무료, 개인회원 유료
        This study examined the use of conjunctions in Korean high school EFL learners’ writings in two discourse modes–description and argument. A corpus of seventy-six descriptive essays and eighty argumentative essays was developed, in which the essays were rated based on their cohesiveness and divided into three groups by their grades. Conjunctions were analyzed based on Halliday and Hasan’s (1976) framework: additive, adversative, causal, and temporal conjunctions. The results revealed different trends of using conjunctions in the two different discourse modes. The descriptive writings with high scores on cohesion tend to exhibit more conjunctions when compared to lower-quality writings, and the argumentative writings with high scores showed fewer conjunctions. The high-quality writings in descriptive mode showed highly frequent uses of additives and adversatives, while those in argumentative mode displayed a lower frequency of additives and a more frequent use of adversative however. Small numbers of causal and temporal conjunctions were used in both discourse modes, and they were particularly limited in descriptive writings regardless of the cohesiveness of writings. This implies that more explicit instructions on causal and temporal conjunctions for each mode are needed in the writing classes. In addition, the scores on cohesion were significantly lower for the descriptive essays than for the argumentative essays, and a much narrower range of conjunctions was employed in descriptive writing. These results suggest a more balanced focus on various discourse modes of writing and the introduction of conjunctions that are appropriate for each mode, since the ability to use conjunctions in one mode does not seem to be automatically transferred to another mode in high school EFL learners’ writings.
        5,500원
        3712.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        There are studies on the assessment of non-edible transgenic plants on soil microbial communities. In this research we evaluated the effect of virus-resistant trigonal cactus on soil microbial communities of the rhizosphere. Soil samples are collected and compared in genetically modified (GM) and non-GM trigonal cactus cultivation fields during vegetative growth period and post-harvest period. Biolog EcoplateTM was used to evaluate the functional diversity of soil microbial communities. There were no significant differences between the GM and non-GM soil samples collected during the vegetative growth period. However, we observed temporary difference in carbon substrate utilization. Principal component analysis showed that soil microbiota was influenced not by presence of GM or non-GM trigonal cacti, but rather by the cultivation period. Denaturing gradient gel electrophoresis fingerprinting revealed that virus-resistant trigonal cactus cultivation had insignificant effect on soil microbial communities including dominant rhizosphere bacteria, actinomycetes, and fungi. We found no clear evidence of GM trigonal cactus cultivation affecting the functional diversity of soil microbial communities.
        4,000원
        3713.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study aimed to evaluate the damage persistence during subsequent years in kiwifruit vines defoliated by strong wind such as typhoons. Artificial defoliation was treated on five-year-old ‘Jecy Gold’ kiwifruit vines grown in a plastic house in year 2013 and 2014 by applying four levels of defoliation, i.e., 0, 50, 75, and 100% in August 23, 2013 and 100% defoliation in July 28 and August 29, 2014, respectively. Return bloom and fruit quality were investigated in the following two years, 2014 and 2015. A significant reduction in number of flowers per shoot in the following year, 2014 was recorded for the vines with 50%, 75%, and 100% defoliations treated in 2013 compared to the control vines. The number of flowers per florescence was significantly reduced for defoliated vines. Nevertheless, the fruit quality parameters, i.e., fruit length, width, weight, firmness, TSS, acidity, and dry matter content were not significantly different for the defoliated vines compared to the control vines. The vines defoliated in 2013 at 75% and 100% levels showed a significant reduction of number of flower per inflorescence in 2015 compared to the 0% defoliation. However, the number of flowers per shoot and fruit quality were not significantly different. Also, the number of flowers per inflorescence in 2015 was significantly reduced by July 28, 2014 or August 29, 2014 defoliation compared to non-defoliated vines while the number of flowers per shoot, and fruit quality in 2015 were not significantly different between treatments and control vines. Accordance with the present findings, the flowering is considerably affected by the shortage of carbohydrate supply than the fruit quality of ‘Jecy Gold’ kiwifruit. In addition, the negative impacts of severe defoliation in flowering of ‘Jecy Gold’ kiwifruit might be persisted more than one season from the time of defoliation and consequently, the total yield might be reduced in the following seasons after defoliation.
        4,000원
        3714.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A study was conducted to evaluate the effects of auxin, cytokinin, and their combined application to hasten their propagation using leaf cuttings. Different hormone levels were evaluated on two Echeveria species (E. subsessilis and E. runyonii). Three levels of auxin as represented by the use of indole-3-butyric acid (IBA) (0, 100, and 500 ppm), three cytokinin levels as represented by Kinetin (Ki) (0, 100, and 200 ppm) and their combination were applied and observed for 8 weeks. The use of 100 ppm IBA resulted in the highest shoot height, diameter, and rooting and shooting rate. Using 500 ppm IBA led the roots to develop the earliest but both species also had the highest mortality. The application of 100 ppm Ki significantly affected the majority of leaf cuttings of E. runyonnii which exhibited the highest and thickest shoots, and the number of leaves. The application of 100 ppm IBA and 100 ppm Ki is recommended to obtain increased shoot growth and development for leaf cuttings. In the case of single hormone use, the application of 100 ppm IBA may be preferable. The combination of auxin and cytokinin significantly stimulated the hastening of production of succulents using leaf cuttings.
        4,000원
        3715.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Growth and development of succulents were studied in response to two leaf cutting types, the tip and base, using four Echeveria species (E. ‘A Grimm One’, E. ‘Momorato’, E. pulvinata ‘Frosty’, and E. pulidonis) and the planting position, either upright and faced-downward, using Graptoveria optalina. The shoot diameter (mm), height (mm), and number of leaves were significantly affected by the leaf cutting type. Results revealed that the shoot diameter of buds from base leaves were significantly larger by 4 - 9 times than those of buds from tip leaves. Shoot height of buds from tip leaves either not developed or reached a maximum of 2.29 mm while buds from base leaves had an average height of 11.61 mm from E. ‘Mamorato’. Using base leaves allowed to obtain roots and leaves for all selected succulent species after 60 days from planting. Regarding planting position, upright planted and downward-facing plants showed significant differences: buds from upright planting showed taller shoots, greater number of leaves which in turn gave higher visual quality rating and superior color reading using Hunter’s Cielab compared with buds in downward-facing planting position. Planting succulents in an upright position led to well-formed shoots and roots which had a high-quality rating and color evaluation compared with faced-downward planting producing etiolated and abnormal grown shoots. Based on these findings, we suggest that the use of base leaf cuttings and an upright planting position provides a rapid vegetative propagation method for selected succulent varieties.
        4,000원
        3716.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to identify the main floral scents and their relative contents in the floral organ of Nelumbo nucifera. N. nucifera flower, a traditional Chinese medicinal herb, is rich in volatile compounds. In this study, the volatile components of N. nucifera flowers were investigated by headspace solid-phase microextraction gas chromatography-mass spectrometry for each organ of the flower: petals, sepals, pistils, and stamens. In total, we identified 39 compounds, among which aliphatics were major constituents, representing more than 94% of petals and sepals volatiles, followed by sesquiterpenes representing more than 69% of pistils and stamens volatiles. Pentadecane, 1-pentadecene, 8-hexadecyne, 8-heptadecene, and β-caryophyllene characterize the scent of the N. nucifera flower. We identified 24 volatiles in petals and sepals, 25 volatiles in pistils, and 18 volatiles in stamens. Among the monoterpenes, 3-Isopropylidene-4-methylcyclohexene, isoterpinolene, p-Menth-2-en-7-ol, and methyl 2,6,6- trimethylcyclohex-1-enecarboxylate were analyzed and identified for the first time from the N. nucifera flower. This study demonstrates that N. nucifera flowers differ greatly in volatile composition depending on the floral organ of the plant.
        4,000원
        3717.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The production scale of mushrooms in Korea is approximately 600 billion won, which is 1.6% of Korea’s gross agricultural output. In Korea, ca. 190,000 tons of mushrooms are harvested annually. Although the numbers of mushroom farms and cultivators are constantly decreasing, total mushroom yields are increasing owing to large-scale cultivation facilities and automation. The recent expansion of the well-being trend has caused an increase in mushroom consumption in Korea: the annual per capita mushroom was 3.9 kg (’13), whichis a little higher than that in Europe. Thus, mushroom export, mainly Flammulina velutipes and Pleurotus ostreatus, has increased since the mid-2000s. Recently, however, it is slightly reduced. Nevertheless, Vietnam, Hong Kong, the United States, and the Netherlands continue to export mushrooms, and Korea has increased its export to Australia, Canada, Southeast Asia, etc. Canned Agaricus bisporus, the first export of the Korean mushroom industry, reached it speak sales in 1977-1978. When Korea initiated trade with China in 1980, the international prices of mushrooms fell sharply, leading to shrinkage of the domestic markets. Spurred by the high demand to develop substitute goods for A. bisporus, the oyster mushroom (P. ostreatus) gained attention since it seemed to suit the taste of Korean consumers. Although the log cultivation technique for oyster mushroom was developed in the early 1970s, it required a great deal of labor. Thus, we developed the shelf cultivation technique, which is easier to manage and allows for mass production. In this technique, the growing shelf is made mafrom fermented rice straw, whichis the only P. ostreatus medium in the world and isused only in South Korea. After then, the use of cotton wastes as an additional material of medium, the productivity. Currently, we are developing a standard cultivation technique and environmental control system that can stably produce mushrooms throughout the year. The increase of oyster mushroom production may boostthe domestic market and contribute to industrial development. In addition, oyster mushroom production technology played a role in forming the basis for the development of bottle cultivation, which made mass production . In particular, bottle cultivation using liquid spawn could allow for the export of F. velutipes and Pleurotus eryngii. In addition, the white varieties of F. velutipes were second developed in the world after Japan. We also developed the new A. bisporus cultivar ‘Saeah’, which is easy to grow in Korea. In hopes to advance the mushroom industry, we will continue to develop cultivars with international competitive power and to improve cultivation techniques.
        4,000원
        3718.
        2016.12 구독 인증기관 무료, 개인회원 유료
        This research is about visualizing data for efficient use in agriculture, by measuring the understanding of graphs according to their features. A questionnaire consisting of one graph, either a bar graph or line graph, and a question about data, was made. According to the results, the time spent answering the question did not differ between the line graph and the bar graph. However, the rate of correct answers differed: that of the bar graph was 50% and the line graph was 0%. This implies that participants answered using the bar graph more accurately regarding whether the data involved understanding the absolute value. From this result, it is clear that using proper features of graphs according to the characteristics of data improves the understanding of information. In addition, a strategy to utilize information and communication technology in agriculture effectively was discussed.
        4,000원