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        검색결과 157

        63.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The sintering mechanisms of nanoscale copper powders have been investigated. A molecular dynamics (MD) simulation with the embedded-atom method (EAM) was employed for these simulations. The dimensional changes for initial-stage sintering such as characteristic lengths, neck growth, and neck angle were calculated to understand the densification behavior of copper nano-powders. Factors affecting sintering such as the temperature, powder size, and crystalline misalignment between adjacent powders have also been studied. These results could provide information of setting the processing cycles and material designs applicable to nano-powders. In addition, it is expected that MD simulation will be a foundation for the multi-scale modeling in sintering process.
        4,000원
        64.
        2015.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Flowering responses under night interruption (NI) condition were determined in Doritaenopsis ‘Fuller’s Sunset ’, ‘Green Beer’, ‘Little Gem Stripes’, and ‘Queen Beer’ during their reproductive stages. Plants were grown under 10/14 h ambient light/dark (control), 10 h ambient light with night interruption (22 : 00-02 : 00 HR) at low light intensity of 3-7 μmol • m−2 • s−1 (LNI) and 10 h ambient light with NI at high light intensity of 120 μmol • m−2 • s−1 (HNI) conditions after flower spike emergence. Time to visible bud and flowering decreased more in the plants grown under HNI than those grown under LNI or control conditions. The number of buds or flowers increased in the plants grown under both LNI and HNI conditions compared to those grown under control condition for all cultivars. The tallest plants at flowering were in the HNI group in ‘Queen Beer’, ‘Green Beer’, and ‘Fuller’s Sunset’, however, the plant height was not significantly different among the treatments in ‘Little Gem Stripes’. NI with low light intensity or high light intensity can be used effectively to promote flower opening, but not with low light intensity at flower development stage. To obtain early flowering with high quality plants using NI treatment during their reproductive stage, high light intensity strategies could be suggested in Doritaenopsis cultivation.
        4,000원
        65.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To compensate for the critical shortage of human organs for allotransplantation, xenotransplantation studies using genetically modified pigs are being performed in Korea. Two types of pigs that are used are α1,3-galactosyltransferase gene knockout (GalT KO) pigs and GalT KO+hCD46 (human complement regulatory protein) pigs. The present study measured the gestation time, birth weight, daily growth rate, and heart weight of both kinds of transgenic minipigs. The gestation period for both types of pigs was 117∼119 days. There was no difference in the body weight of GalT KO (—/+) and GalT KO (—/—) piglets, but GalT KO+hCD46 (—hCD46+/+) pigs were significantly heavier at birth than were GalT KO+hCD46 (—hCD46+/—hCD46+) pigs. During the first 10 weeks of life, the daily weight gain of GalT KO+hCD46 (—hCD46+/—CD46+) piglets, which are considered the optimal type for xenotransplantation, was 0.19 kg. The weight of hearts from GalT KO piglets up to two months of age was affected more by body weight than by age. Transgenic pigs showed no differences in gestation period or reproductive ability compared with normal pigs. These results comprise basic data that may be used in xenotransplantation studies and transgenic animal production in Korea.
        4,000원
        66.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 다양한 높이에 따른 철골 중간모멘트골조의 내진성능을 평가하는 것이다. 구조물의 내진성능은 ATC-63에서 제안한 방법론에 따라 평가되었다. 3층, 6층, 9층, 12층 중간모멘트골조의 설계는 KBC 2009에 따라 수행하였다. 접합부의 모델링은 철골 중간모멘트골조에서 요구되는 회전성능인 0.02rad을 만족하도록 모델링하였다. 연구를 수행한 결과, 구조물의 붕괴확률은 높이가 증가함에 따라 증가하였다. 특히 9층과 12층 구조물은 ATC-63에서 제시한 요구조건을 만족하지 못하였다.
        4,000원
        69.
        2013.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study assesses of efficiency of oocyte recovery and in vitro development for during the non breeding season in goat. Thirty-four matured goats, maintained in a pen under natural day length and fed hay ad libitum, were pretreated with progestagen implanted CIDR for 10 days. Superovulation treatment of the goats received twice daily intramuscular injections of a total of 70 mg FSH for 3 days from Day 8 of CIDR. All the gonadotropin treated goats were injected with 10 mg PGF2α on Day 8 and 400~600 IU hCG in the afternoon on Day 10. Oocytes were recovered by follicle aspiration or oviduct flushing at 35 to 40 h after hCG injection through mid-ventral incision. The in vivo matured oocytes were activated by ionomycin (5 min) and 6-DMAP (3.5~4 h). The activated oocytes were cultured in mSOF medium containing 0.8% BSA at 38.5℃ in an atmosphere of 5% CO2, 5% O2, 90% N2 for 7~8 days. There was no significant difference in the mean number of CL and in vivo matured and follicular oocytes recovered. But, quality of I+II grade follicular oocytes was lower (p<0.05) in the prepubertal goat (25.0%) than the adults (52.4%). The same results were also observed in the cleavage and blastocyst rate of activated oocytes. The clavage and blastocyst rate from prepubertal derived oocytes were lower (p<0.05) in the prepubertal goat (54.5%, 23.3%) than the adult goat (86.8%, 46.6%). Considering overall these results, we suggest that maturation of donor goats is a major factor affecting recovered oocytes quality and in vitro development of activated goat oocytes. There was no significant difference in oocyte quality between seasonal treatments.
        4,000원
        70.
        2012.06 구독 인증기관 무료, 개인회원 유료
        This study aims to examine the effect of Genetically Modified β -Carotene Biofortified Rice rice developed by simultaneous expression technology in NAAS on biological immunity. Accordingly, this study added Genetically Modified β-Carotene Biofortified Rice 25, 50% and general rice 50% as control group into diet and provided rats with the prescribed feeds and then measured the contents of immunoglobulin and cytokine in blood. As a result, male and female IgM, IgE, male IgG1, female IgG2a and TNF-a, IL5 and IL12 showed no significant difference; male IgG2a tended to decrease dependently on the combined concentration of Genetically Modified β-Carotene Biofortified Rice; female IgG1 showed significance with control group, but its association with diet was not found. The higher the dietary mixing ratio, the more the male and female IFN-a and female IL-4 contents, regardless of rice variety, and it was found that female IL6 content decreased significantly, but its association with diet was not found. The risk of beta carotene-enriched rice into environment and human body has not been reported yet. The digestion of Genetically Modified β-Carotene Biofortified Rice can be seen as "safe" as this test result showed no big difference between general rice and Genetically Modified β-Carotene Biofortified Rice, and its usability is full of suggestions.
        4,000원
        71.
        2012.05 구독 인증기관·개인회원 무료
        This study was conducted to identify an insect species in Genus Ostrinia (Lepidoptera: Crambidae) that gave serious damage to the red bean, Vigna angularis. The species has ever been described as O. zaguliaevi in the previous presentation (Jung et al., 2010). Because, however, inconsistent information has been recognized for the species, we reviewed characteristics in morphological, molecular and sex pheromone levels, and host-range. Male genitalia had 3-lobed uncus and tibia of midleg showed massive type. The morphology indicated that the species might be one of O. zaguliaevi, O. scapulalis and O. zealis. Partial nucleotide sequences of cytochrome oxidase subunit Ⅰ(COⅠ) and Ⅱ genes were not identical with those of the 3 species in GenBank, respectively. The deduced amino acid sequence of COⅠ was not identical with that of O. zealis. In the 23 analyses that sex pheromones were checked, (Z)-9-tetradecenyl acetate, which was reported in the sex pheromone components of both O. zaguliaevi and O. zealis, was not detected at all. An intensive study in Japan has reported that the feeding habit of O. scapulalis is polyphagous, while that of O. zaguliaevi is monophagous (only in Petasites japonicus) (Ishikawa et al., 1999). After considering all these information, we concluded that it is reasonable to decide that the insect species in the red bean in Korea is O. scapulalis.
        72.
        2011.12 구독 인증기관 무료, 개인회원 유료
        Pneumatosis cystoides intestinalis (PCI) is a rare condition characterized by multiple intramural pockets of gas filled cysts in the intestinal wall. PCI is usually found incidentally on an imaging study. Many different causes of PCI have been suggested, including mechanical, pulmonary, and bacterial causes. Treatment is usually conservative, including oxygen and antibiotic therapy. We report on two cases of PCI, without symptoms, in a 62-year-old male and a 72-year-old male. Computed tomography showed numerous, small, round, and air densities on the sigmoid colon. Colonoscopy showed numerous, variable-sized, sessile polypoid, balloon-like distended, and protruding subepithelial masses covered with normal colonic mucosa on the sigmoid colon. We observed that when the cyst was stuck with a needle, the size of the cyst was reduced and showed a flat termination. Therefore, we made a diagnosis of PCI and report on the case with references.
        4,000원
        75.
        2010.10 구독 인증기관·개인회원 무료
        The genus Lilioceris Reitter, 1912, containing generally thirty species of two subgenera, is distributed Oriental regions (Gressit and Kimoto, 1961). Seven species were recorded in Korea (Lee and An, 2001). Many of them are important pests on medicinal plants and garden flowers (lily, yam, etc). There have been a few studies on the adult taxonomy of Korean Lilioceris (Gressitt and Kimoto, 1961; An et al., 1986; An and Kwon, 1995, An, 1995, 1996, 1998, Lee and An, 2001). Although the main damage to the plants is caused by their larvae, nothing is known about the immature stages of Korean Lilioceris. L. (L.) ruficollis is associated with the host plants of Dioscorea (Dioscoreaceae), especially D. septemioba which is a well-known medicinal plant in Korea. In the present paper, detailed descriptions and illustrations of the immature stages of L. (L.) ruficollis are provided for the first time. Some remarks on their biology are also given.
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