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        검색결과 875

        505.
        2010.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We develop a proto-model of an off-axis reflective telescope for infrared wide-field observations based on the design of Schwarzschild-Chang type telescope. With only two mirrors, this design achieves an entrance pupil diameter of 50 mm and an effective focal length of 100 mm. We can apply this design to a mid-infrared telescope with a field of view of 8 ̊ X 8 ̊. In spite of the substantial advantages of off-axis telescopes in the infrared compared to refractive or on-axis reflective telescopes, it is known to be difficult to align the mirrors in off-axis systems because of their asymmetric structures. Off-axis mirrors of our telescope are manufactured at the Korea Basic Science Institute (KBSI). We analyze the fabricated mirror surfaces by fitting polynomial functions to the measured data. We accomplish alignment of this two-mirror off-axis system using a ray tracing method. A simple imaging test is performed to compare a pinhole image with a simulated prediction.
        4,500원
        507.
        2010.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of high energy ball-milling (HEBM) on the sintering behavior and piezoelectric properties of 0.1 wt% doped 0.8Pb()-0.2Pb() (PMN-PZT) ceramics were investigated. It was found that HEBM treatment was quite effective to reduce the average particle size down to 300 nm, leading to increased density as well as enhanced piezoelectric properties of a sintered specimen even though prolonged HEBM resulted in unwanted secondary phases that caused a degradation of piezoelectric properties. The dielectric constant (), piezoelectric coupling factor () and piezoelectric constant of 0.1 wt% doped PMN-PZT ceramics prepared via HEBM for 10 h reached 2040, 0.68 and 554 pC/N, respectively.
        4,000원
        508.
        2010.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of doping on the crystal structure, ferroelectric, and piezoelectric properties of (K,Na) (KNN) ceramics have been investigated. was found to be effective in enhancing the densification and grain growth during sintering. X-ray diffraction analysis indicated that Mn ions substituted B-site Nb ions up to 2 mol%, however, further doping induced unwanted secondary phases. In comparison with undoped KNN ceramics, the well developed microstructure and the substitution to B-sites in 2 mol% Mn-doped KNN ceramics resulted in significant improvements in both piezoelectric coupling coefficient and electromechanical quality factor.
        4,000원
        509.
        2010.10 구독 인증기관·개인회원 무료
        Pine wilt disease (PWD) represents a major threat to forest ecosystems worldwide. Although PWD is now better understood, effective control measures for this disease have still not been devised. Here, we report several years of field studies on preventative silvicultural control of PWD. Silvicultural control through preventative clear-cutting and the manual removal of logs was implemented between 2005 and 2009 in 16 Korean districts that had newly PWD-infected stands. Preventative clear-cutting of neighbouring asymptomatic pine trees (within a 10 to 50-m radius ofwilt trees) and the removal of felled logs or branches suppressed spread of PWD. Occurrences of PWD wilt pines in districts (city or county) subjected to this silvicultural control method were significantly reduced compared with those in districts using conventional controls (physical or chemical treatment of wilt pine trees). Through silvicultural control, PWD was successfully suppressed in 11 of 16 districts investigated. In contrast, successful control was achieved in only 1 among 18 districts subjected to conventional control. Our results will be of considerable interest to those engaged in the very difficult battle against the global spread of PWD.
        510.
        2010.10 구독 인증기관·개인회원 무료
        Scirtothrips dorsalis Hood is a newly advent pest on citrus in Jeju. Both larvae and adult attack the new shoots and young and matured fruits of citrus. S. dorsalis is highly polyphagous with over 100 recorded species, but not known in Jeju. As a result from investigating the host plants in and/or around citrus orchards in Jeju during 2009 to 2010, they were 25 families 39 species. The total thrips examined on those plants were 13 species, and the richness thrips among them was S. dorsalis, Frankliniella occidentalis, Thrips tabaci and Thrips hawaiiensis. The widespread host plants of S. dorsalis were Mallotus japonicus, Paederia scandens, Hedera rhombea, Cayratia japonica and Clematis apiifolia and they can be also used for monitoring plants. On early May, the larvae of S. dorsalis were first investigated on the shoots of Mallotus japonicus, Lonicera japonica, Paederia scandens, Viburnum awabukira, Fraxinus rhynchophylla and Celtis sinensis. The other thrips species except S. dorsalis and T. tabaci, especially F. intonsa, T. hawaiiensis, T. flavus and T. coloratus were just found on flower stalks during the blooming season.
        511.
        2010.10 구독 인증기관·개인회원 무료
        The diapause duration P. ussuriensis eggs is known to either one year or prolonged to additional years. This complex life cycle is mainly caused by the interruption at two embryonic stages: early stage (initial diapause) and fully developed late stage (final diapause). The environmental cues, such as temperature, is critical to determine the diapause duration but the precise diapause mechanism of P. ussuriensis eggs is unclear. We demonstrated temperature effects on the entrance of initial diapause. Newly oviposited eggs were incubated at two temperature conditions (20℃and 30℃) for 60 days. When eggs were incubated at 20℃, egg weights were not significantly changed, but at 30℃ those were gradually increased to 1.5 times for 50 days. Genomic DNA contents of eggs were similarly increased at 30℃. Total RNA contents at 30℃ were highly increased from the 15-days-old but not at 20℃. In addition, we further analysed expression levels of two heat shock protein 70 (hsp70a, hap70b) genes during embryonic development. Our results suggest that initial diapause occurred between 10 and 15 days after oviposition and its entrance was blocked by high temperature incubation.
        512.
        2010.10 구독 인증기관·개인회원 무료
        The oral toxicities of symbiotic bacteria Photorhabdus temperata ssp temperata (Ptt), mutually associated with entomopathogenic nematode Heterorhabditis megidis, and P. luminescens ssp. laumondii (TT01) with H. bacteriophora, were demonstrated to adults of the sweetpotato whitefly Bemisia tabaci. Sucrose solution (25%) containing bacteria-free supernatant of culture media of symbiotic bacteria was ingested into adult whiteflies within the glass tube. Whitefly mortalities were shown similar patterns against two bacterial media. Mortalities were significantly increased to 60-64% at 36 hours and almost 100% at 60 hours after treatments. In addition, We demonstrated the effect of oral ingestion of symbiont culture media on the gene expression of B. tabaci. Several genes fluctuated those expression levels. Our results suggest that oral ingestion of symbiont culture media of entomopathogenic nematodes significantly changed metabolic rates and highly lethal to whiteflies. The use of symbiotic bacteria of entomopathogenic nematodes provides a great potential as an alternative genetic resource of Bacillus thuringiensis, a major resource of microbial insecticide.
        513.
        2010.10 구독 인증기관·개인회원 무료
        As an natural enemy against the Monochamus alternatus Hope and M. saltuarius Gebler (Coleoptera: Cerambycidae), the vector species of the pine wood nematode (Bursaphelenchus xylophilus (Steiner & Buhrer), Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is recognized for the first time in Korea. The family Bothrideridae is also reported for the first time in Korea. We provide the diagnosis, illustrations, biological information, and the host insects of D. helophoroides (Fairmaire).
        514.
        2010.10 구독 인증기관·개인회원 무료
        Spider mites are one of major pests in cultivations of various ornamental plants and also important in plant quarantine service. Due to the very small body size and high similarity within the Genus the identification of species is difficult even at the microscopic observation. To identify 5 major species (Tetranychus cinnabarinus, T. urticae, T. phaselus, T. kanzawai and T. truncatus) in the Genus Tetranychus at the molecular level, we designed 4 species-specific primer sets using nucleotide sequences of the internal transcribed spacer (ITS2) region in the nuclear ribosomal repeat unit. At the PCR diagnosis of extracted genomic DNAs of 5 species using each primer set, specific primers of both T. phaselus and T. truncates were species-specific to their own species samples. However, specific primer set of T. urticae detected T. cinnabarinus as well as T. urticae. Specific primer set of T. kanzawai detected T. truncates as well as T. kanzawai, even though detection intensities were lower in non-target species.
        515.
        2010.10 구독 인증기관·개인회원 무료
        As a member of fungus gnats, the genus Bradysia can be the pests on many kind of agricultural crops, including mushroom farming. Feeding on healthy roots of crops, they can also spread root rot diseases. In Korea Bradysia difformis is known as major pest in greenhouse crops (carrot, cucumbers, garlic, melon, potatoes, radish, strawberries, sugarbeet, sweetpepper, sweetpotato, etc). Besides Bradysia difformis, we report six Bradysia species for the first time in Korea.
        516.
        2010.10 구독 인증기관·개인회원 무료
        The Phylinae plant bugs dealt with 9 species in 3 genera in tribe phylini. A new genus Badephylus gen. nov. with a species B. sobaeksana sp. nov. is proposed here. Four species: Campylomma chinense Schuh, 1984; C. miyamotoi Yasunaga, 2001; Europiella artemisiae (Becker, 1864) and E. kiritshenkoi Kulik, 1975 are recognized for the first time in Korea. Keys are provided to distinguish Korean Capylomma and Europiella. Photos of Dorsal habitus, male genital structures for each species are provided with their host informations.
        517.
        2010.06 KCI 등재 구독 인증기관·개인회원 무료
        Methanol and hot water extracts of Suillus granulatus were investigated for its antioxidant activity, polyphenol content and tyrosinase inhibitory effect. The antioxidant activity was evaluated using 1, 1- dipheny l-2-picrylhydrazyl (DPPH) scavenging assay. The antioxidant activities of hot water and 80% methanol extracts of Suillus granulatus fruiting body were 51.49%. and 90.58% at 1.5mg/ml concentration. Total polyphenol content of hot water and 80% methanol extracts were 33.21㎍ GAEs/mg and 27.97㎍ GAEs/mg. Tyrosinase inhibitory activity of water extract was 7.8% while 80% methanol extract was 20.88% at 1mg/ml concentration.
        518.
        2010.06 KCI 등재 구독 인증기관·개인회원 무료
        Methanol and hot water extracts of Daedalea bien-nis were investigated for its antioxidant activity, poly- phenol content and tyrosinase inhibitory effect. The antioxidant activity was evaluated using 1, 1-diphenyl -2-picrylhydrazyl (DPPH) scavenging assay. The antioxidant activities of hot water and 80% methanol extracts of Daedalea biennis fruiting body were 52.06%. and 92.62% at 1.5mg/ml concentration. Total polyphenol content of hot water and 80% methanol extracts were 12.26㎍ GAEs/mg and 13.69㎍ GAEs/mg. Tyrosinase inhibitory activity of water extract was 19.70% while 80% methanol extract was 15.75% at 1mg/ml concentration.