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        검색결과 182

        42.
        2018.10 구독 인증기관·개인회원 무료
        Whitefly (Hemiptera: Aleyrodidae) pests, including the tobacco whitefly, Bemisia tabaci, and the greenhouse whitefly, Trialeurodes vaporariorum, are economically important in agriculture. With the annual growth of the domestic fresh fruit export market, various quarantine treatment methods are being used to export strawberries of better quality. The objective of the present study was to evaluate the effects of gamma rays on the development and reproductive sterility of B. tabaci and T. vaporariorum. In both species, the eggs were completely inhibited from hatching at 50 Gy, and the emergence of 3rd instar nymphs was completely suppressed at 150 Gy. Some adult B. tabaci and T. vaporariorum spawning occurred at 100 Gy and 70 Gy, respectively; however, at these irradiation levels, F1 hatchability was completely inhibited. Dosimetry results showed that the penetrating power of gamma ray in the strawberry-filled box was the lowest at the mid-box position. Therefore, B. tabaci and T. vaporariorum were placed in the middle of the strawberry-filled box and irradiated. A gamma-ray irradiation of 100 Gy suppressed the development and reproduction of eggs and adults in both B. tabaci and T. vaporariorum. However, the development of 3rd instar nymphs was inhibited at 300 Gy for B. tabaci and 200 Gy for T. vaporariorum. Our data suggest that at least 300 Gy should be used for the control of these two types of whitefly for strawberry export.
        50.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A signi cant number of the parameters of a gamma-ray burst (GRB) and its host galaxy are calculated from the afterglow. There are various methods obtaining extinction values for the necessary correction for galactic foreground. These are: galaxy counts, from HI 21 cm surveys, from spectroscopic measurements and colors of nearby Galactic stars, or using extinction maps calculated from infrared surveys towards the GRB. We demonstrate that AKARI Far-Infrared Surveyor sky surface brightness maps are useful uncovering the ne structure of the galactic foreground of GRBs. Galactic cirrus structures of a number of GRBs are calculated with a 2 arcminute resolution, and the results are compared to that of other methods.
        3,000원
        51.
        2017.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        감마분광분석 시스템 상에서는 226Ra(186.2 keV)과 235U(185.7 keV)가 방출하는 감마선 에너지의 피크 중첩이 발생한다. 226Ra의 직접분석을 위해서는 중첩된 피크로부터 235U의 기여를 제거해주거나 보정상수를 이용하여 실제 226Ra의 방사능 값 으로 보정 해주어야 한다. 235U가 방출하는 다른 감마선 피크를 참조하여 235U의 기여를 제거할 경우 복잡한 수계산이 필요하며, 참조피크에서 기인하는 큰 불확도로 인해 높은 정량한계를 갖는다. 반면에 보정상수를 이용하여 226Ra을 평가할 경우 간단한 계산으로 평가가 가능하며, 간접측정시 요구되는 222Rn의 용기건전성과 방사평형 복구기간이 필요하지 않아 226Ra의 신속 측정시 유용한 방법이다. 따라서 해당 방법을 통해 원료물질 3종과 공정부산물 3종, 총 93여개 시료에 대해서 보정상수로 산출된 226Ra의 방사능 농도와 방사평형 된 214Bi의 방사능 농도의 비교를 통해 유효성을 확인하였다. 대부분 ± 20% 내에서 유효하였지만 인산석고의 경우 약 50%의 오차를 보였다. 이는 보정상수를 유도하기 위한 가정 중 238U과 226Ra의 방사평형 관계가 달라진 것으로 판단된다. 특이성을 반영한 보정상수를 적용하여 226Ra의 방사능 농도에 대한 유효성을 평가한 결 과 약 ±10%로 좀 더 정밀한 결과를 얻을 수 있었다. 본 연구에서 산출된 보정상수를 통한 226Ra의 방사능 농도 평가 방법은 복잡한 수계산이 필요하지 않고 용기선택으로부터 자유로우며 방사평형 복구를 위한 기간이 필요하지 않아 원료물질 및 공정부산물의 226Ra의 신속한 농도 분포 평가시 유효한 방법이다.
        4,000원
        52.
        2016.05 구독 인증기관·개인회원 무료
        Crosslinked ion exchange resin composite membranes were prepared by casting sulfonated polystyrene(SPS) solution with suspended ion exchange resin(crosslinked SPS) and crosslinker (trimethylolpropane ethoxylate triacrylate (TMPETA)) follow by gamma-ray irradiation. The physicochemical properties of the composite membranes were evaluated by measuring gel-fraction, ion exchange capacity, water-uptake and dimensional stability. We confirmed that the introduction of ion exchange resin and radiation crosslinking in the membranes improved the water uptake, dimensional stability and permselectivity.
        56.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present results of long-term multi-wavelength polarization observations of the powerful blazar 3C 279 after its -ray flare on 2013 December 20. We followed up this flare with single-dish polarization observations using two 21-m telescopes of the Korean VLBI Network. Observations carried out weekly from 2013 December 25 to 2015 January 11, at 22 GHz, 43 GHz, 86 GHz simultaneously, as part of the Monitoring Of GAmma-ray Bright AGN (MOGABA) program. We measured 3C 279 total flux densities of 22–34 Jy at 22 GHz, 15–28 Jy (43 GHz), and 10–21 Jy (86 GHz), showing mild variability of ≤ 50% over the period of our observations. The spectral index between 22 GHz and 86 GHz ranged from −0.13 to −0.36. Linear polarization angles were 27◦–38◦, 30◦–42◦, and 33◦–50◦ at 22 GHz, 43 GHz, and 86 GHz, respectively. The degree of linear polarization was in the range of 6–12%, and slightly decreased with time at all frequencies. We investigated Faraday rotation and depolarization of the polarized emission at 22–86 GHz, and found Faraday rotation measures (RM) of −300 to −1200 rad m−2 between 22 GHz and 43 GHz, and −800 to −5100 rad m−2 between 43 GHz and 86 GHz. The RM values follow a power law with a mean power law index a of 2.2, implying that the polarized emission at these frequencies travels through a Faraday screen in or near the jet. We conclude that the regions emitting polarized radio emission may be different from the region responsible for the 2013 December -ray flare and are maintained by the dominant magnetic field perpendicular to the direction of the radio jet at milliarcsecond scales.
        4,000원
        57.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The Interferometric Monitoring of Gamma–ray Bright Active galactic nuclei (iMOGABA) program provides not only simultaneous multifrequency observations of bright gamma–ray detected active galactic nuclei (AGN), but also covers the highest Very Large Baseline Interferometry (VLBI) frequencies ever being systematically monitored, up to 129 GHz. However, observation and imaging of weak sources at the highest observed frequencies is very challenging. In the second paper in this series, we evaluate the viability of the frequency phase transfer technique to iMOGABA in order to obtain larger coherence time at the higher frequencies of this program (86 and 129 GHz) and image additional sources that were not detected using standard techniques. We find that this method is applicable to the iMOGABA program even under non–optimal weather conditions.
        5,400원
        59.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This review summarises the current status of the Galactic TeV (1012 eV) gamma-ray source population. It also brie y looks at the future beyond the current generation of TeV gamma-ray facilities, and highlights the role of the interstellar medium (ISM) in helping to resolve some of the challenges in interpreting the wealth of results which have been found in recent years.
        4,000원
        60.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        방사선 동위원소 코발트(60Co)를 유기원으로 한 100Gy의 감마선을 2008년 5월과 9월 두 번에 걸쳐 ‘Clara’ 품종의 캘러스묘에 24시간 처리하였다. 1차에 감마선을 처리하여 유기된 돌연변이 중 착색엽이 분홍색인 변이지를선발하였다. 2010년까지 포인세티아의 특성을 3차에 걸쳐 검정 한 후 ‘Clara Pink’로 명명하였다. 2차로 감마선을 처리한 캘러스묘에서는 2011년까지 세대를 진전시키면서 형질의 안정성 검토 후 착색엽이 연황색인 변이주를 선발하여 계통화하였다. 2012년부터 2013년까지 3차에 걸쳐 특성 검정하였으며, ‘Clara White’로 명명하였다.‘Clara Pink’와 ‘Clara White’는 ‘Clara’와 같은 소형으로적심하지 않은 상태에서 분지가 많이 발생하였다. 두 품종 모두 착색엽이 결각이 없는 난형으로 엽맥 사이에약한 주름이 있으며, 단일처리 약 9주 후 완전히 착색되었다. 그러나 ‘Clara’의 착색엽은 적색인 반면 ‘ClaraPink’는 분홍색이며, ‘Clara White’는 연황색이다.
        3,000원
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