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        검색결과 804

        381.
        2011.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This paper reports a characteristic motion of a polarity inversion line (PIL) formed at the solar surface, which is newly found by performing a three-dimensional magnetohydrodynamic simulation of flux emergence in the Sun. A magnetic flux tube composed of twisted field lines is assumed to emerge below the surface, forming a bipolar region with a PIL at the surface. A key finding is the successive half-turn rotation of the PIL, leading to the formation of a quadrupolar-like region at the surface and a magnetic configuration in the corona; this configuration is reminiscent of, but essentially different from the so-called inverse-polarity configuration of a filament magnetic field. We discuss a physical mechanism for producing the half-turn rotation of a PIL, which gives new insights into the magnetic structure formed via flux emergence. This presents a reasonable explanation of the configuration of a filament magnetic field suggested by observations.
        4,000원
        385.
        2011.10 구독 인증기관·개인회원 무료
        Gene targeting is a genetic technique that utilizes homologous recombination between an engineered exogenous DNA fragments with the endogenous genome of an organism. In domestic animal, gene targeting has provided an important tool for producing Knock-out pig for GGTA1 gene to use xenotransplantation. The frequency of homologous recombination is a critical parameter for the success of gene targeting. The efficiency of homologous recombination in somatic cells is lower than that in mouse ES cells. So the application of gene targeting in somatic cells has been limited by its low efficiency. Recently, knock-out rat and mouse was generated by introducing nonhomologous end joining (NHE)-mediated deletion or insertion at the target site using zinc-finger nucleases (ZFN). Therefore, the development of effective knock-out and knock-in techniques in domestic animal is very important in biomedical research. In this present study, we investigated whether homologous recombination events occurs at cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) gene locus using ZFN in porcine primary fibroblast. CMAH-targeted ZFN DNA and mRNA were purchased from SIGMA-Aldrich. CMAH neo targeting vector consists of the neomycin resistance gene as a positive selectable marker gene, 789 bp 5’ arm and 763 bp 3’ arm from Exon 8 of CMAH gene. For transfection, the targeting vector and ZFN DNA or mRNA were introduced into ear fibroblasts cells of Chicago miniature pig by electroporation. After selection of G-418, PCR analysis was performed using 213 colonies transfected with ZFN DNA or mRNA. As a result, 39 positive colonies were identified in colonies transfected with ZFN DNA or mRNA. To our knowledge, this study provides the first evidence that the efficiency of gene targeting using ZFN was higher than that of conventional gene targeting in the porcine fibroblast. These cell lines may be used in the production of CMAH knock-out for xenotransplantation.
        386.
        2011.10 구독 인증기관·개인회원 무료
        Covalent modifications of histone tails have fundamental roles in chromatin structure and transcriptional activity of a target locus. One of such modifications, Methylation at Lysine 9 of histone H3 (H3-K9) causes several epigenetic phenomena including heterochromatin formation, transcriptional regulation and DNA methylation. Setdb1, H3-K9 specific histone methyltransferase, functions in gene silencing, heterochromatin formation and essential role for early development. Here, we demonstrate that Setdb1 associates with promyelocytic leukemia (Pml) protein from the early stage of mouse development and is a constitutive member of PML nuclear bodies (PML-NBs) that have been linked to many cellular processes such as apoptosis, DNA damage responses, and transcriptional regulation. Immunostaining of mouse blastocyst showed that Setdb1 and Pml signals were scattered in nucleus as a few speckles and microinjected Pmlmyc signals colocalize with Setdb1 signals. This colocalization was observed in mEF and the punctate signals of Setdb1 were observed to be present in every nucleus of mEFs and dividing cells with condensed chromosomes. Arsenic treatment, which induces Pml degradation, also caused Setdb1 signals to disappear. Setdb1 knockdown resulted in disassembly of PML-NBs and immunoprecipitation results demonstrated physical interactions between Setdb1 and Pml. These data suggest that Setdb1 was associated in PML-NB and Setdb1 has important function in maintenance of PML-NB structure.
        387.
        2011.10 구독 인증기관·개인회원 무료
        Entomopathogenic fungus Aschersonia aleyrodis naturally occurred on citrus whitefly, Dialeurodes citri nymph was often observed in organic citrus orchards, Jeju. The genus Aschersonia is also known to be toxic against scale insects and other pests. However, little is known about artificial media for mass production of spores of Aschersonia species. Grains are excellent sources of media for mass conidia production of various entomopathogenic fungi. The yeast extract, which converts carbohydrates to carbon dioxides and alcohols, contains a large amount of vitamin B complexes which facilitate the carbohydrate metabolism. The more yeast extract content the more conidia production on artificial medium made from commercial corn flour and corn gluten feed. The number of conidium produced on oat, millet, sorghum, and unhulled barley medium containing 1% yeast extract were 1.8, 1.8, 1.6, and 2.1×1010/plate (90mm × 15mm), respectively. However, the greatest yeast effect among four media showed appeared on sorghum medium, which produced 25 times higher spore production than sorghum alone. Furthermore, the conidia from solid sorghum medium could be easily harvested with cell scraper.
        388.
        2011.10 구독 인증기관·개인회원 무료
        Aschersonia aleyrodis was well-known to be a biological control agent for citrus whitefly, Dialeurodes citri. This entomopathogenic fungus is naturally occurred in organic farming citrus orchards in Jeju. Both lime-sulfur and Bordeaux mixtures are extensively used today to control citrus diseases like citrus melanose and citrus scab, especially in organic farming pest management program. The high concentrated lime-sulfur is also used for pest control such as pink citrus rust mite and scale insects. This study was focused to test the conidial germination and sporulation of Aschersonia aleyrodis on potato dextrose agar (PDA) medium containing different concentrations of two fungicides. The conidia of Aschersonia aleyrodis grown on PDA mixed with commercial bordeaux mixtures, CM150-505, at dilution rate 1:200 (water : bordeaux mixture) were well-germinated but not sporulated at all. On the other hand, Aschersonia aleyrodis did not sporulate and germinate on lime sulfur treated PDA medium even at extremely low dilution rate 1:2,048,000 (water : lime sulfur). However, when the mycelial cells grown at 25o C for at least 7 days at soluble starch-tryptone medium were added to PDA, they were well-sporulated even at high dilution rate 1:100 (water : lime sulfur). This result suggested that the spore mixtures of Aschersonia aleyrodis should be applied to field quite long after lime-sulfur spray.
        389.
        2011.10 구독 인증기관·개인회원 무료
        Riptortus clavatus is one of the most serious pests affecting the cultivation of sweet persimmon, which is one of the most important export fruits in Korea. A pheromone-baited trap has been used in attempts to control this pest. Although the trap showed relatively good trap efficacy, it was often observed that R. clavatus walks around and rests on the surface of the trap rather than entering the trap. In the present study, the development of a more efficient pheromone-baited trap for R. clavatus was pursued by investigating 3 different traps: the fish trap, the pyramidal trap, and the symmetry trap. The fish trap captured the lowest number of R. clavatus, and the pyramidal trap showed moderate capture efficacy. Significantly greater numbers of R. clavatus adults were captured in the symmetry trap. Significantly increased trapping efficacy of the symmetry trap would be useful for mass trapping of R. clavatus.
        390.
        2011.10 구독 인증기관·개인회원 무료
        Beet armyworm (BAW), Spodoptera exigua (Hübner), is a polyphagous lepidopteran pest mainly distributed in tropical and subtropical regions. BAW are known to migrate long distances to find suitable host plants and environmental condition. The possibility of its overwintering in temperate regions has been suspected. This study was conducted for investigating overwintering and phenology of BAW using by sex pheromone trap in Jeju during 2007 to 2011. BAW was able to overwinter at pupae stage regardless of temperature of winter season in Jeju. The times of BAW caught first on traps were different by surveyed years - early March in 2007, middle March in 2008 and 2011 and early April in 2009 and 2010. The times of BAW caught on trap tended to be more dependent on temperature variation during on November and December than on mean temperature of winter season. The peak season of adults of the overwintering generation was early to middle of May. The results of seasonal periodicity of BAW monitored by sex pheromone trap during 2009 and 2010 indicated that five generations were passed in Jeju. The peak season of 1st generation was on middle of April, 2nd generation on middle of July, 3rd generation on early of August, 4th generation on late of August and 5th generation on middle of September. There were similar patterns by different above sea levels except the season of overwintering generation adults occurrence (March to May).
        391.
        2011.09 구독 인증기관 무료, 개인회원 유료
        4,000원
        392.
        2011.06 구독 인증기관 무료, 개인회원 유료
        This study was conducted in order to evaluate the effect of sericin-calcium (SC) as therapy for ovariectomy-induced osteoporosis in rats. Three weeks after ovariectomy (OVX), Sprague-Dawley rats were divided randomly into three groups: sham-operated group (Sham), ovariectomized group, and SC-treatment group (OVX+SC). Rats in the OVX+SC group were given drinking water containing 0.07% SC for eight weeks. Bone breaking force, mineralization, and blood parameters related to bone metabolism were analyzed. In OVX animals, blood concentration of 17β-estradiol showed a significant decrease, while osteocalcin and type I collagen C-terminal telopeptides (CTx) showed an increase. Breaking force of femurs as well as bone mineral density (BMD), ash, calcium, and phosphorus in femurs showed a significant decrease following OVX. Treatment with SC (0.07% in drinking water) resulted not only in remarkable restoration of the decreased 17β-estradiol and increased osteocalcin and CTx concentrations, but also led to recovery of decreased femoral breaking force, BMD, ash, calcium, and phosphorus. It is suggested that SC effectively improves bone density by preventing bone turnover-mediated osteocalcin, CTx, and minerals, and that it could be a potential candidate for use in therapy or prevention of post-menopausal osteoporosis.
        4,200원
        393.
        2011.06 구독 인증기관 무료, 개인회원 유료
        Liver cancer represents a major health problem with steadily increasing incidence rates. Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third most common cause of cancer-related death. This study was conducted in order to investigate the gross findings following treatment with diethylnitrosamine (DEN) in mice. Sixteen male and female mice (B6C3F1), initially 20 days of age, received intraparietal injection (20 mg/kg three times for a period of two weeks, IP) or were given drinking water (DW) containing 50 ppm DEN; all mice were sacrificed at the 80th week of experiments. Hepatocellular adenoma (HCA) and HCC were induced in B6C3F1), mice by administration of DEN. The numbers of HCA and HCC were 7.4±1.72 (IP) and 7.2±0.86 (DW) in male mice. However, no significant difference was observed between the DW and IP groups. The numbers of HCA and HCC were 0.67±0.33 (IP) and 2.0±0.63 (DW) in female mice. This study showed a tendency for high incidences of liver tumor with long-term exposure of newborn animals by drinking water.
        4,000원
        394.
        2011.05 구독 인증기관·개인회원 무료
        Arrowhead scale, Unaspis yanonensis, is a serious scale insect pest of citrus in Jeju. The sticky taping of 1.0 cm diameter twig was a good survey method for arrowhead scale crawler. There are three times crawler occurrence season - late May to early July, late July to middle September and late September to late October. But the third occurred crawlers are all died during overwintering in open-field groves. This study was conducted to provide information on efficient sampling plan for arrowhead scale within the tree. Twig and fruit was fit for secondary sample unit by two-stage variance analysis. Both sample number per tree (primary sample unit) was eight twigs or fruits. Taylor’s power law was better described the distribution characteristic of arrowhead scale than Iwao’s patchiness regression. The slope of both linear regressions was greater than “1” which means aggregative distribution pattern. Minimum sample size to estimate the density was calculated using by two parameters of Taylor’s power law. To estimate the mean density on twig and fruit by binomial sampling plan, the optimum tally threshold was 5 and 7, respectively.
        397.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study was an attempt to investigate a Cognitive Academic Language Proficiency (CALP) theme with the Interdependence Hypothesis in the use of Content-Based Instruction (CBI) approach. In addition, the study examined the threshold notion of language proficiency and how it would play in different groups distinguished by school level. Based on the analyses of data obtained from comprehension quizzes, proficiency tests of speaking and writing, questionnaire, and interview, the study revealed that the undergraduate group showing a higher level of proficiency and the graduate group experiencing longer period of schooling performed on the comprehension quizzes and evaluated their CBI experiences similarly. It suggested that CALP represented by schooling earned in L1 be taken advantage of as a springboard for CBI. It also indicated that reading skills may be more critical to the survival and success in CBI courses at least for the participants of the current study who showed relatively high confidence in listening skills. It suggested that there is a need for further study to examine whether such a tendency is common to the similar groups of Korean English language learners in order to accommodate their preferred way of learning English.
        8,600원
        398.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        공학적 안전설비 공기정화계통과 관련된 실험 수행을 위해 원자력등급 ESF 공기정화계통 시뮬레이터 를 설계, 제작, 검증하였다. 영광 5,6호기 주제어실 공기정화계통의 공급자 정보, 도면 등을 기준으로 실 사를 통해 치수를 확인하여 3D CAD 모델을 작성하였다. 모델과 현장 계통의 실측 유량을 기준으로 CFD 분석을 수행하였다. 공기정화계통으로 유입되는 공기는 30 ℃, 유동형태는 균일한 것으로 가정하고, 검사 기록지에 의한 주제어실 ESF 공기정화계통의 유량이 12,986 CFM이고, 610×610 ㎟의 HEPA 필터가 9개 설치되어 있으므로 HEPA 필터 단면를 지나는 유속은 1.83 m/s이다. 주제어실 공기정화계통 모델링시 공 기 유동이 흐르지 않는 필터 테두리 지지대를 고려하여 현장과 유사한 유동현상을 모사하였다. 약 8 m/s 로 기록된 활성탄 흡착기 하단의 공기유동은 별도의 분석을 통해 7 m/s 이상의 유속이 모사되도록 CFD 분석하였다. 연료건물 비상배기계통 및 비상노심냉각계통 기기실 배기정화계통의 공기정화계통에 대해 서도 CFD 분석한 결과, 시뮬레이터의 유속을 조절하면 세가지 ESF 공기정화계통을 모두 모사할 수 있음 을 확인하였다. CFD 분석 후 시뮬레이터를 원자력등급으로 제작하였고, 본 실험에 착수하기 전에 공기유 동 분포도실험을 통해 시뮬레이터의 신뢰도를 검증하였다. 검증결과 중급 필터를 장착한 상태에서 시뮬 레이터의 필터 지지대 부분을 제외한 내부에서 공기유동이 고르게 분포함을 확인하였고, 제작된 시뮬레 이터는 Reg. Guide 1.52(Rev.3) 개정 내용 확인을 위한 실험에 사용되었다.
        4,000원
        399.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        공학적 안전설비 공기정화계통의 규제지침인 Reg. Guide 1.52(Rev.3)의 변경사항중 성능시험과 관련 한 운전가능성 시험시간 단축, HEPA 필터 현장누설시험용 시험물질 변경 및 활성탄 성능시험 Methyl Iodidie 투과허용율 상향 변경을 영광 5,6호기에 적용하고자, 모사실험장치와 현장 설비를 활용하여 기술 적 타당성을 확인하는 실험을 수행하였다. 10시간 이상의 장시간 운전가능성 시험을 통해 계통내 습분을 제거하여도 시험후 1∼4일만에 회복됨을 확인하여 운전가능성 시험은 기기적 운전가능성 점검에 적합한 매월 15분 이상의 시험을 수행하는 것이 타당함을 확인하였다. HEPA 필터 현장누설시험용 시험물질 변 경을 위해 DOP와 PAO의 에어로졸 입자크기, 발생량, 누설인지도를 비교한 결과 PAO는 원전에서도 DOP 대체시험물질로 사용 가능함을 확인하였다. 베드깊이 4 인치 이상의 활성탄여과기에 대한 Methyl Iodide의 투과율 허용치가 0.175 %에서 0.5 %로 상향 변경된 것은, ASTM D3803(1989)으로의 활성탄 성 능시험 방법 변경에 따른 것으로서, 30 ℃ 상대습도 95 %에서의 Methyl Iodide 투과허용율 0.5 %가 사용 중 활성탄의 성능을 시험하기에 충분히 보수적인 시험방법임을 확인하였다. 본 실험 결과를 바탕으로 영 광 5,6호기는 인허가변경을 완료하였다.
        4,000원