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        검색결과 569

        121.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Acoustics are increasingly regarded as a remote-sensing tool that provides the basis for classifying and mapping ocean resources including seabed classification. It has long been understood that details about the character of the seabed (roughness, sediment type, grain-size distribution, porosity, and material density) are embedded in the acoustical echoes from the seabed. This study developed a sophisticated yet easy-to-use technique to discriminate seabed characteristics using a split beam echosounder. Acoustic survey was conducted in Tongyeong waters, South Korea in June 2018, and the verification of acoustic seabed classification was made by the Van Veen grab sampler. The acoustic scattering signals extracted the seabed hardness and roughness components as well as various seabed features. The seabed features were selected using the principal component analysis, and the seabed classification was performed by the K-means clustering. As a result, three seabed types such as sand, mud, and shell were discriminated. This preliminary study presented feasible application of a sounder to classify the seabed substrates. It can be further developed for characterizing marine habitats on a variety of spatial scales and studying the ecological characteristic of fishes near the habitats.
        4,200원
        122.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pigs are considered as optimal donor animal for the successful xenotransplantation. To increase the possibility of clinical application, genetic modification to increase compatibility with human is an important and essential process. Genetic modification technique has been developed and improved to produce genetically modified pigs rapidly. CRISPR/Cas9 system is widely used in various fields including the production of transgenic animals and also can be enable multiple gene modifications. In this study, we developed new gene targeting vector and enrichment system for the rapid and efficient selection of genetically modified cells. We conducted co-transfection with two targeting vectors for simultaneous inactivation of two genes and enrichment of the genetically modified cells using MACS. After this efficient enrichment, genotypic analysis of each colony showed that colonies which have genetic modifications on both genes were confirmed with high efficiency. Somatic cell nuclear transfer was conducted with established donor cells and genetically modified pigs were successfully produced. Genotypic and phenotypic analysis of generated pigs showed identical genotypes with donor cells and no surface expression of α-Gal and HD antigens. Furthermore, functional analysis using pooled human serum revealed dramatically reduction of human natural antibody (IgG and IgM) binding level and natural antibody-mediated cytotoxicity. In conclusion, the constructed vector and enrichment system using MACS used in this study is efficient and useful to generate genetically modified donor cells with multiple genetic alterations and lead to an efficient production of genetically modified pigs.
        4,000원
        123.
        2018.12 구독 인증기관 무료, 개인회원 유료
        There have long been debated whether Jeju king cherry in Korea and Punus x yedoensis (Yoshino cherry) in Japan are the same or not and its originality. Recent genomic approach among P. yedoensis and closed related varieties from Korea, Japan and USA confirms that P. yedoensis is F1 hybrid. The results also show that there are two types of Jeju king cherry in Mt. Halla, Jeju, Korea and one type is clearly different and the other type is the same grouping to Yoshino cherry in Japan and USA and the maternal texa of the two types in Jeju is the same of P. pendula. The search of paternal texa of the same type and further molecular genetic analysis and classification among newly found hundreds of Jeju King Trees in natural habitats of Mt. Halla including a 265 year-old tree along with previous findings would reveal the hypothesis that two independent F1 hybrid of P. yedoensis are evolved in Mt. Halla where is the only natural birth place of P. yedoensis in the world. Furthermore, policy agenda of king cherry tree eco-exploration among six countries including two divided Korea proposed. In terms of bio-diplomacy, it was amazing fact that Jeju King Cherry trees were sent USA under Japanese colony in 1912. In 1943, USA Congressman John Rankin of Mississippi confirms that they were Korean Cherry Trees. The first four of these trees were presented to the American University in 1943 by the Korean Women’s Relief Society of Honolulu according to notice of AU’s School authority. As Jeju NAtional University students and teachers confirmed the fact in April 2018, they suggest Jeju King Cherry Trees Eco- Exploration between the two universities at university level, hoping to extend a warming program of planting Jeju King Cherry trees at the Dalma tourism complex in Wonsan city of North Korea in April of 2020.
        4,000원
        124.
        2018.12 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to determine if natural extracts could be used as an additive in oral health food made with Weissella cibaria CMU (oraCMU). Natural extracts of green tea, mulberry leaf, licorice, and propolis, which are reported to have antimicrobial activities, were selected and used in this study. The minimum inhibitory concentrations (MIC) of extracts on periodontal pathogens such as Fusobacterium nucleatum and Porphyromonas gingivalis and their synergy effects with oraCMU by the fractional inhibitory concentrations methods were measured. From the results obtained, all the extracts showed no effect on the growth of oraCMU. Green tea extract showed the best antibacterial activity with MIC of 1.8 mg/ml against both F. nucleatum and P. gingivalis. In addition, green tea extract had a synergistic effect with oraCMU against F. nucleatum. Therefore, these results suggested that green tea extract is available as an additive in oral health food made with oraCMU.
        4,000원
        125.
        2018.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study examined EFL college-level learners’ perception toward the contentbased instruction (CBI) by focusing on their participation in and expectation on the courses practiced in a strong form of CBI. Having analyzed the data collected from a questionnaire, observation and interview, the study found that the participants, 39 students who enrolled in two different CBI courses at a university in South Korea, put top priority on the enhancement of content-knowledge considering their CBI course as a content-course, not as a language-course. Second, the participants seemed to prefer participation opportunities induced by a required and prepared speaking task such as presentation through which they can practice a formal speech appropriate for their education experience and cognitive maturity. They also seemed to favor instructor-initiated interaction rather than being put into pair- or group-discussion between and among themselves. Third, the lack of participation was mainly attributed to the lack of understanding contents rather than lack of language skills. Based on the research findings, the study made suggestions on how to offer CBI courses more effectively for a particular group of EFL college-level learners who already earned basic interpersonal communication skills (BICS), yet to reach cognitive academic language proficiency (CALP).
        8,100원
        136.
        2018.10 구독 인증기관·개인회원 무료
        Insecticidal and repellent effects of herb extracts were tested against Aedes albopictus and Ochlerotatus togoi that are common among mosquitoes which inhabit Korea. Herb extracts from Mentha×piperita, Ocimum basilicum, and Nepeta cataria were extracted using distilled water and 70% ethanol respectively. Both kinds of mosquitoes were raised in environment control rearing system with air temperature of 25℃, humidity of 70%, and light condition of 14:10(L:D). Insecticidal effect was verified by feeding extracts to mosquitoes(Park et al., 2016.); repellent effect, by measuring their radial distance from extract by time. N. cataria extract using distilled water as a solvent is predominant in insecticidal effect; O. basilicum, using 70% ethanol. In particular, N. cataria has the most outstanding repellent effect.
        137.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It has been reported that gastrocnemius tightness and posterior talar glide are crucial factors influencing ankle dorsiflexion. However, the relationship of ankle dorsiflexion and these factors is not identified in previous studies. The purpose of this study was to identify the relationship of ankle dorsiflexion passive range of motion and gastrocnemius tightness and posterior talar glide. Twenty-five male subjects participated in this study. Bilateral weight-bearing ankle dorsiflexion passive range of motion and amount posterior talar glide of participants were measured using an inclinometer. Change in myotendinous junction of medial gastrocnemius was measured using ultrasonography to identify gastrocnemius tightness. Pearson product moment correlations were performed to examine correlations between ankle dorsiflexion passive range of motion and gastrocnemius tightness and posterior talar glide. Present findings revealed significant correlation between ankle dorsiflexion passive range of motion and gastrocnemius tightness (p=0.017, r=0.336). Also, ankle dorsiflexion passive range of motion was correlated with posterior talar glide (p=0.001, r=0.470). The present findings provide experimental evidence for factors influencing weight-bearing ankle dorsiflexion.
        3,000원
        138.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the SW industry, the diversification of global markets and technology trends are changing due to the emergence of new services, and IT companies are in need of strategic change different from the previous one. In this study, SWOT analysis was performed by extracting the internal environmental factors and external environmental factors through the previous studies to improve the project performance competence of small IT companies, and the SWOT Matrix was reconstructed through the pairwise comparison. Based on this, the purpose of this research was to propose the project performance competency improvement plans for small IT companies based on importance and priority, and the following four strategies were derived from the result of SWOT-AHP analysis. SO strategy was drawn in direction to invest R & D in new SW industry to enhance technology competitiveness of SMEs in order to develop SMEs, and in order to secure competitiveness of SW industry, WO strategy is drawn the cultivation of professional technical manpower through SW policy. ST Strategy presented technical management through SW system improvement policy to improve SW environment, and WT Strategy presented awareness training on the construction and necessity of project management system construction. Using the strategies presented in this study, it is expected that the managers of small IT firms will be presented as references to measure the performance competence factors of current organizations and company organizations.
        4,000원
        139.
        2018.09 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        This study was carried out to investigate the protective effect of prednisolone in rabbit primary cultured articular chondrocytes treated with sodium nitroprusside (SNP), a nitric oxide donor. After a cell phenotype was determined, the MTT assay and Western blot analysis of type II collagen, cylooxygenase-2 (COX-2) and phosphorylated extracellular regulated kinase (pERK) were performed in the control, SNP (298 μg/ml) alone or SNP plus prednisolone (0.05-50 μg/ml)-treated rabbit articular chondrocytes. Immunofluorescence staining of type II collagen was also performed. Cell morphology indicated that SNP treatment induced cytotoxicity, and that the SNP-induced cytotoxicity was inhibited by prednisolone treatment. MTT assay showed that the SNP treatment resulted in a significant decrease in the level of cell viability compared with that of control (p<0.01), and that the prednisolone treatment resulted in a decrease in the SNP-induced cytotoxicity. SNP treatment resulted in a decrease in the level of type II collagen, compared with the control chondrocytes. The prednisolone treatment recovered the down-regulated expression of type II collagen induced by SNP, showing a significant level in 5 μg/ml of the prednisolone treatment group compared to the SNP treatment group (p<0.05). A significant increase in COX-2 was significantly induced by the SNP treatment compared to control chondrocytes (p<0.01). The COX-2 expression was decreased by the prednisolone treatment, showing a significant level in 50 μg/ml of the prednisolone treatment group compared to the SNP treatment group (p<0.05). These phenomena was confirmed by immunofluorescence staining. Furthermore, the SNP treatment significantly induced a decrease of pERK expression compared to the control chondrocytes (p<0.01). The prednisolone treatment recovered its expression, showing a significant level in 0.5 μg/ml of the prednisolone treatment group compared to the SNP treatment group (p<0.05). Taken the above results together, prednisolone is considered to inhibit SNP-induced cell death and dedifferentiation, and modulated expression of COX-2 and pERK in rabbit articular chondrocytes.
        4,000원
        140.
        2018.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Effect of the nonuniform grid on the two-dimensional transport equation was investigated in terms of theoretical analysis and finite difference method (FDM). The nonuniform grid having a typical structure of the numerical weather forecast model was incorporated in the vertical direction, while the uniform grid was used in the zonal direction. The staggered and non-staggered grid were placed in the vertical and zonal direction, respectively. Time stepping was performed with the third-order Runge Kutta scheme. An error analysis of the spatial discretization on the nonuniform grid was carried out, which indicated that the combined effect of the nonuniform grid and advection velocity produced either numerical diffusion or numerical adverse-diffusion. An analytic function is used for the quantitative evaluation of the errors associated with the discretized transport equation. Numerical experiments with the non-uniformity of vertical grid were found to support the analysis.
        4,000원