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        검색결과 79

        21.
        2018.05 구독 인증기관·개인회원 무료
        Roller Compacted Concrete Pavement (RCCP) is placed by roller compaction of a mixture of less cement and unit water content and more aggregates and provides excellent early strength development with the help of interlocking of aggregates and hydration. The unit cement content of RCC pavements accounts for 85% of conventional pavements, with low drying shrinkage. As low drying shrinkage leads to smaller crack widths than ordinary concrete, RCC pavements can help elevate reflecting crack resistance if applied to a base layer of a composite pavement system. In a composite pavement with an asphalt surface laid over a concrete base, pavement temperature change is important in predicting pavement performance. As movement of the lower concrete layer is determined by temperature depending on pavement depth, temperature data of the pavement structure serves as an important parameter to prevent and control reflecting crack. Among the causes of reflecting crack, horizontal behavior of the lower concrete layer and curling-caused vertical behavior of joints/cracks are considered closely related to temperature change characteristics of the lower concrete course (Baek, 2010). Previous studies at home and abroad about reflecting crack have focused on pavement behavior depending on daily and yearly in-service temperature changes of a composite pavement (Manuel, 2005). Until now, however, studies have not been conducted on initial temperature characteristics of concrete in composite pavements where asphalt surface is placed over an RCC base. Annual temperature changes of in-service concrete pavements go up to 60 ℃, and those of asphalt overlays become around the twice at 110 ℃. This study evaluated initial crack behavior of composite pavement by investigating pavement temperature by depth of an RCC base and analyzing joint movement depending on change to temperatures of continuously jointed pavements. Findings from the study suggest that in composite pavements and asphalt overlays, time of laying asphalt has an important impact on crack behavior and reflecting crack.
        23.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We demonstrated an effective way of preparing melt spinnable mesophase pitches via catalytic hydrogenation of petroleum residue (fluidized catalytic cracking-decant oil) and their subsequent thermal soaking. The mesophase pitches thus obtained were analyzed in terms of their viscosity, elemental composition, solubility, molecular weight, softening point and optical texture. We found that zeolite-induced catalytic hydrogenation under high hydrogen pressure contributed to a large variation in the properties of the pitches. As the hydrogen pressure increased, the C/H ratio decreased, and the solubility in n-hexane increased. The mesophase pitch with entirely anisotropic domains of flow texture exhibited good meltspinnability. The mesophase carbon fibers obtained from the catalytically hydrogenated petroleum residue showed moderate mechanical properties.
        4,000원
        24.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The seroprevalence of major infectious abortion agents was investigated in native Korean goats from Jeonnam province using ELISA. A total of 98 blood samples were collected from goats. Overall, 48 (49.0%), 11 (11.2%), and 1 (1.0%) serum samples tested positive for C. burnetii, T. gondii, and C. abortus, respectively, while none of the samples were positive for B. abortus or N. caninum. Moreover, a PCR assay conducted to detect C. burnetii antigens in goats with a history of abortion revealed 18 (38.3%) of 47 goats were C. burnetii positive by both the ELISA and PCR assay.
        4,000원
        25.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Changes in land use and increase in urban energy consumption influence urban life. This study analyzed the characteristics and patterns of urban heat and presents management schemes to generate a comfortable and sustainable urban environment. The study aimed to demonstrate the positive effects of artificial ground greening on improving the microclimate through evapotranspiration using perennial herbs. We have designed a chamber that could control constant temperature and humidity, measure temperature reductions in each plant and changes in sensible heat and latent heat. This study identified Sedum kamtschaticum as the most effective plant in controlling temperature. At 22℃, 3.2℃ temperature reduction was observed, whereas four other plants showed a 1.5℃ reduction. At 25℃, 2.0℃ temperature reduction was observed. On the other hand, the use of Sedum sarmentosum resulted in the lowest effect. Zoysia japonica is the most commonly used ground covering plant, although the temperature reduction of Lysimachia nummularia was more effective at high temperature conditions. Sensible heat and latent heat were calculated to evaluate the thermal performance of energy. At a temperature >30℃, L. nummularia and S. sarmentosum emitted high latent heat. In this study, we analyzed the thermal performance of green roof perennial plants; in particular, we analyzed the evapotranspiration and temperature reduction of each plant. Since the substrate depth and types, plant species, and seasonal change may influence temperature reduction and latent heat of green roofs, further studies are necessary.
        4,000원
        27.
        2014.10 구독 인증기관·개인회원 무료
        In this study, the following four species are reported for the first time in Korea: Diplopseustis perieresalis (Walker, 1859), Dolicharthria bruguieralis (Duponchel, 1833), Herpetogramma ochrimaculale (South, 1901), and Omiodes diemenalis (Guenée, 1854). All of the known species were enumerated with their available information including the collecting localities, host plants, illustrations of adults, and genitalia.
        28.
        2014.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The adsorption of volatile organic compounds (VOCs) was carried out using an activated carbon fiber (ACF) filter in an automobile. The adsorption capacities of formaldehyde, toluene, and benzene on an ACF filter were far better than those of a polypropylene (PP) mat filter and combined (PP+activated carbon) mat filter by batch adsorption in a gas bag. In a continuous flow of air containing toluene vapor through an ACF packed bed, the breakpoint time was very long, the length of the unused bed was short, and sharp "S" -type breakthrough curve was plotted soon after breakpoint, showing a narrow mass transfer zone of toluene on the ACF. The adsorption amount of toluene on the ACF filter was proportional to the specific surface area of the ACF; however, the development of mesopores 2-5 nm in size on the ACF was very effective with regard to the adsorption of toluene. The ACF air clarifier filter is strongly recommended to remove VOCs in newly produced automobiles.
        4,000원
        29.
        2014.04 구독 인증기관·개인회원 무료
        Urbanization is one of the leading causes of habitat loss, habitat degradation, and fragmentation. Urban development negatively affects biodiversity. This study aimed to clarify the change of butterfly communities on effect of urbanization in urban green areas. Butterfly survey was conducted using the line transect methods from April to October in 2012. A total of 59 species and 1,465 individuals of butterflies were observed in four urban green areas: Namsan Park (NS), Ewha Womans University (EW), Bukseoul Dream Forest (BD), and Hongneung Forest (HF), and natural forest: Gwangneung Forest (GF). The category of land use around study site was determined based on GIS data. Species richness and abundance of niche breadth and habitat type in urban green areas differed significantly from those in GF. Estimated species richness and species diversity (H’) in four urban green areas were significantly lower than those in GF. Species richness and abundance of forest interior species and specialist were positively correlated with paddy, field, and forest, whereas those of forest interior species and specialist were negatively correlated with urban area and road. Butterfly communities in four urban green area differed from that in GF. The result suggests that the decrease of paddy, field, and forest associated with increase of urban area and road negatively influences species composition and changes butterfly communities.
        31.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        선충절대기생세균(Pasteuria penetrans)이 감염되어 있는 온실토양을 이용하여 세균의 내생포자가 땅콩뿌리혹선충(Meloidogyne arenaria) 유충 표면에 부착하는데 대한 온도의 영향에 대해 시험하였다. 갓 부화된 뿌리혹선충 2령충(J2)을 페트리디쉬 내의 토양에 접종한 후 20℃, 25℃, 30℃, 35℃에서 7일간 처리하였다. 모든 온도에서 내생포자의 J2 부착률은 모두 100%로 나타났으나 J2당 내생포자 부착수는 25℃에서 28.3개로 가장 많았으며 30℃, 20℃ 및 35℃에서 각각 J2 당 20.2, 18.6 및 13.6개로 낮아졌다. J2를 접종하기 전에 세균이 있는 토양을 온도 별로 10일간 전처리하였을 때 내생포자 부착률은 실온에서의 60%에 비해 -30℃, 4℃, 40℃, 50℃ 및 100℃에서 각각 25.0, 31.7, 8.3, 5.0 및 0%로 현저하게 낮아졌다. J2 당 내생포자 부착수도 실온에서의 5.3개에 비해 -30℃, 4℃, 40℃, 50℃ 및 100℃에서 각각 3.5, 4.3, 1, 1, 0개로 적었다. P. penetrans 세균의 내생포자를 뿌리혹선충 종별로 J2에 부착 시험한 결과 땅콩뿌리혹선충에서는 100%였으나 당근뿌리혹선충(M. hapla)과 고구마뿌리혹선충(M. incognita)에서는 모두 0%로 본 균주는 뿌리혹선충 종에 대해 기주선호성을 가진 것으로 나타났다.
        4,000원
        32.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The recent development in genetic assisted selection (combining traditional- and genome assisted selection method) and reproduction technologies will allow multiplying elite cow in Hanwoo small farm. This review describes the new context and corresponding needs for genome assisted selection schemes and how reproductive technologies can be incorporated to get more genetic gain for cow genetic improvement in Hanwoo. New improved massive phenotypes and pedigree information are being generated from commercial farm sector and these are allowing to do genetic evaluation using BLUP to get elite cows in Korea. Moreover cattle genome information can now be incorporated into breeding program. In this context, this review will discuss about combining the reproductive techniques (Multiple Ovulation Embryo Transfer; MOET) and genome assisted selection method to get more genetic gain in Hanwoo breeding program. Finally, how these technologies can be used for multiplication of elite cow in small farm was discussed.
        4,000원
        33.
        2013.04 구독 인증기관·개인회원 무료
        The bulb mite (Rhizoglyphus echinopus) damages garlic, shallot and onion in the bulbs, corms and tubers. It has recently become a serious problem because of the continuous use of acaricides resulting in resistance among bulb mite population. Thus, there is need to find alternative control measures to suppress bulb mite population. Here, we report the screening result of pathogenic fungi for the control of R. echinopus. Initial screenings were performed using 352 isolates of entomopathogenic fungi from Korea soils. As results, 15 isolates of acaropathogenic fungi showed the pathogenicity to bulb mite supporting fungal conidiation. These isolates were identified as 3 isolates of Metarhizium flavoviride var. pemphigi and 12 isolates of Metarhizium pingshaense by microscopic examination and genetic sequencing of the ITS region and elongation factor-1 alpha. Selected 15 isolates were tested for their virulence against adult R. echinopus and the thermotolerance and the activity to UV-B irradiation of conidia. Additionally, the activities of chitinases and proteases produced by M. pingshaense were compared according to the medium. These acaropathogenic fungi would be considered promising for biological control of bulb mite.
        34.
        2012.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study examined whether vocabulary knowledge has meaningful effects on reading comprehension of Korean high school EFL learners and investigated which specific type of vocabulary knowledge, between vocabulary breadth and depth, plays a bigger role in reading comprehension when the learners’ English language proficiency is taken into account. The participants of this study were ninety eight high school EFL learners in Seoul, Korea, and they were tested on a series of measures tapping on their reading comprehension abilities and vocabulary knowledge in two different dimensions (vocabulary breadth and depth). Their listening comprehension abilities were also measured in order to control for the effects of general oral language comprehension abilities known to be the foremost contributor to reading comprehension and thus to enable focused analysis of the role of vocabulary knowledge. The study findings revealed that 1) vocabulary knowledge itself played a critical role in predicting reading comprehension abilities even after controlling for their listening comprehension abilities and that 2) compared to vocabulary breadth, vocabulary depth played a relatively more important role in predicting reading comprehension, regardless of the learners’ language proficiency. The findings provide important implications for vocabulary and reading comprehension instructions for Korean EFL students.
        6,000원
        36.
        2011.03 구독 인증기관 무료, 개인회원 유료
        The faulty regulation of imprinting gene lead to the abnormal development of reconstructed embryo after nuclear transfer. However, the correlation between the imprinting status of donor cell and preimplantation stage of embryo development is not yet clear. In this study, to determine this correlation, we used the porcine spermatogonial stem cell (pSSC) and fetal fibroblast (pFF) as donor cells. As the results, the isolated cells with laminin matrix selection strongly expressed the GFRα-1 and PLZF genes of SSCs specific markers. The pSSCs were maintained to 12 passages and positive for the pluripotent marker including OCT4, SSEA1 and NANOG. The methylation analysis of H19 DMR of pSSCs revealed that the zinc finger protein binding sites CTCF3 of H19 DMRs displayed an androgenic imprinting pattern (92.7%). Also, to investigate the reprogramming potential of pSSCs as donor cell, we compared the development rate and methylation status of H19 gene between the reconstructed embryos from pFF and pSSC. This result showed no significant differences of the development rate between the pFFs (11.2±0.8%) and SSCs (13.3±1.1%). However, interestingly, while the CTCF3 methylation status of pFF-NT blastocyst was decreased (36.3%), and the CTCF3 methylation status of pSSC-NT blastocyst was maintained. Therefore, this result suggested that the genomic imprinting status of pSSCs is more effective than that of normal somatic cells for the normal development because the maintenance of imprinting pattern is very important in early embryo stage.
        4,000원
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