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        검색결과 58

        1.
        2023.10 구독 인증기관·개인회원 무료
        Honey bees are crucial pollinators for agricultural and natural ecosystems, but are experiencing heavy mortality in Korea due to a complex suite of factors. Extreme winter losses of honey bee colonies are a major threat to beekeeping but the combinations of factors underlying colony loss remain debatable. Finding solutions involves knowing the factors associated with high loss rates. To investigate whether loss rates are related to Varroa control and climate condition, we surveyed beekeepers in korea after wintering (2021–2022 to 2022–2023). The results show an average colony loss rate of 46%(2022) and 17%(2023), but over 40% colony loss before wintering at 2022. Beekeepers attempt to manage their honey bee colonies in ways that optimize colony health. Disentangling the impact of management from other variables affecting colony health is complicated by the diversity of practices used and difficulties handling typically complex and incomplete observational datasets. We propose a method to 1) Varroa mite population Control by several methods , and 2) Many nursing bee put in hive before wintering.
        4.
        2023.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The second generation of stars in the globular clusters (GCs) of the Milky Way (MW) exhibit unusually high N, Na, or Al, compared to typical Galactic halo stars at similar metallicities. The halo field stars enhanced with such elements are believed to have originated in disrupted GCs or escaped from existing GCs. We identify such stars in the metallicity range −3.0 < [Fe/H] < 0.0 from a sample of ∼36,800 giant stars observed in the Sloan Digital Sky Survey and Large Sky Area Multi-Object Fiber Spectroscopic Telescope survey, and present their dynamical properties. The N-rich population (NRP) and N-normal population (NNP) among our giant sample do not exhibit similarities in either in their metallicity distribution function (MDF) or dynamical properties. We find that, even though the MDF of the NRP looks similar to that of the MW’s GCs in the range of [Fe/H] < −1.0, our analysis of the dynamical properties does not indicate similarities between them in the same metallicity range, implying that the escaped members from existing GCs may account for a small fraction of our N-rich stars, or the orbits of the present GCs have been altered by the dynamical friction of the MW. We also find a significant increase in the fraction of N-rich stars in the halo field in the very metal-poor (VMP; [Fe/H] < −2.0) regime, comprising up to ∼20% of the fraction of the N-rich stars below [Fe/H] = −2.5, hinting that partially or fully destroyed VMP GCs may have in some degree contributed to the Galactic halo. A more detailed dynamical analysis of the NRP reveals that our sample of N-rich stars do not share a single common origin. Although a substantial fraction of the N-rich stars seem to originate from the GCs formed in situ, more than 60% of them are not associated with those of typical Galactic populations, but probably have extragalactic origins associated with Gaia Sausage/Enceladus, Sequoia, and Sagittarius dwarf galaxies, as well as with presently unrecognized progenitors.
        4,800원
        5.
        2023.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the result of a high-resolution spectroscopic study on seven magnesium (Mg) enhanced stars. The high Mg abundances in these stars imply that they were born in an environment heavily affected by the nucleosynthesis products of massive stars. We measure abundances of 16 elements including Mg and they show various abundance patterns implying their diverse origin. Three of our program stars show a very high Mg to Si ratio ([Mg/Si] ≈ 0.18–0.25), which might be well explained by fall-back supernovae or by supernovae with rapid rotating progenitors having an initial mass higher than about 20 𝑀⊙. Another three of our program stars have high light to heavy s-process element ratios ([Y/Ba] ≈ 0.30–0.44), which are consistent with the theoretical prediction of the nucleosynthesis in rapidly rotating massive stars with an initial mass of about 𝑀 = 40 𝑀⊙. We also report a star having both high Y ([Y/Fe] = 0.2) and Ba ([Ba/Fe] = 0.28) abundance ratios, and it also shows the highest Zn abundance ratio ([Zn/Fe] = 0.27) among our sample, implying the nucleosynthesis by asymmetric supernova explosion induced by very rapid rotation of a massive progenitor having an initial mass between 20 𝑀⊙ ≲ 𝑀 ≲ 40 𝑀⊙. A relative deficiency of odd-number elements, which would be a signature of the pair-instability nucleosynthesis, is not found in our sample.
        4,300원
        7.
        2022.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present a method to determine nitrogen abundance ratios with respect to iron ([N/Fe]) from molecular CN-band features observed in low-resolution (R ∼ 2000) stellar spectra obtained by the Sloan Digital Sky Survey (SDSS) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Various tests are carried out to check the systematic and random errors of our technique, and the impact of signal-to-noise (S/N) ratios of stellar spectra on the determined [N/Fe]. We find that the uncertainty of our derived [N/Fe] is less than 0.3 dex for S/N ratios larger than 10 in the ranges Teff = [4000, 6000] K, log g = [0.0, 3.5], [Fe/H] = [−3.0, 0.0], [C/Fe] = [−1.0, +4.5], and [N/Fe] = [−1.0, +4.5], the parameter space that we are interested in to identify N-enhanced stars in the Galactic halo. A star-by-star comparison with a sample of stars with [N/Fe] estimates available from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) also suggests a similar level of uncertainty in our measured [N/Fe], after removing its systematic error. Based on these results, we conclude that our method is able to reproduce [N/Fe] from low-resolution spectroscopic data, with an uncertainty sufficiently small to discover N-rich stars that presumably originated from disrupted Galactic globular clusters.
        4,600원
        14.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        갓과 대의 색택이 백색인 백색느타리 신품종『백선』의 주요특성은 다음과 같다. 균사생장적온은 28~31 o C이고 버섯발생온도는 22 o C, 버섯생육온도 20 o C로 ‘미소’보다 균사생장적온이 높으며 버섯발생 및 생육온도가 유사하며, 발생형은 다발형태를 나타내었다. 병재배시 배양기간은 30일, 초발이 소요일수는 4일, 생육일수는 4일로 총재배 기간은 38일이 소요되었다. 형태적 특성에 있어 갓직경은 32.5 mm, 대직경 9.1 mm, 대길이 91.4 mm로 ‘미소’에 비하여 가늘고 긴 형태를 나타내었으며, 갓색도(L)는 84.2, 대색도(L)은 83.4로 ‘미소’에 비하여 밝은 백색을 나타내었다. 수량은 생산력 검정시 1100 ml병에서 185 g을 나타내었으며, 농가실증재배시 A(평택) 184g/1100 ml, B(여주) 178 g/850 ml으로 대조품종 대비 40%이상 증수 되었다. 대의 물리성은 탄력성, 응집성, 씹음성, 깨짐성이 각각 80%, 57%, 720 g, 57 kg을 나타내었다. DNA다형성을 비 교 분석한 결과 UFPF1, UFPF3, UFPF4의 primer에서 교배모본인 ‘GMPO20410’와 ‘MGL2205’의 DNA의 밴드가 혼합되어 있었으며 품종 간, 균주 간의 밴드 차이가 있 었다. 저장기간에 따른 신선도는 4 o C에서 28일 저온저장 시 8점으로 신선한 상태였으며, 4 o C저장 후 상온보관 시 5점으로 식용 가능한 상태로 대조품종인 ‘미소’ 보다 저온 및 상온보관 시 신선도가 우수하였다.
        4,000원
        15.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        국제적으로 신품종과 품종 육성자의 권리가 지적 재산권으로 보호됨에 따라 화훼작물의 경우 국내 민간종묘에서 품종 개발이 거의 이루어지지 않아 농촌진흥청 원예시험장(구 국립 원예특작과학원) 화훼과에서 1992년부터 본격적으로 품종육성 연구가 시작되었다. 2017년 재배면적 44ha, 판매액 93.6억원 인 주요 난류의 하나인 심비디움은 다른 화종에 비해 육종년 한이 길어 2002년에 ‘뷰티프린세스’ 등 4품종이 육성된 후 2017년까지 51품종이 육성되었고, 농촌진흥청 연구비 지원으로 지산영농조합법인에서도 ‘핑크레이스’ 등 26품종이 육성된 바 있다. 이렇게 개발된 품종은 농가에 보급되어 분화나 절화 로 유통되고 있어 최근에는 국산 품종에 대한 재배농가의 인지도가 높아지고 있다. 2009년부터 2017년까지 aT화훼공판장 에서 거래되고 있는 국산 심비디움 품종들의 분화 거래내역을 조사한 결과, 농촌진흥청 개발 51품종 중 21품종이 지산영농 조합 개발 26품종 중 7품종이 1년에서 5년동안 거래된 것을 확인하였다. 국산 품종 거래 수는 2010년과 2015년을 제외하고는 2,568~5,693분으로 총 심비디움 판매량의 1.5~2.1%를 차지하였다. 심비디움 거래량의 65.2~97.6%를 차지하는 꽃대 2, 3, 4대 가격을 비교한 결과, 국산 품종이 외국산 품종에 비하 여 최고가는 낮았지만 평균가는 높았고, 최저가는 훨씬 높았다. 결론적으로 aT화훼공판장 거래가를 기준으로 국산 품종이 외국산 품종과 비교할 때 품질이 양호하였음을 알 수 있었다.
        4,000원
        16.
        2019.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution ($R\sim6000$) spectra of these stars to estimate the abundances of several chemical elements (Mg, Si, Ca, Ti, Cr, Fe, and Ni), and derived their space velocities and orbital parameters using proper motions from the \gaia\ Data Release 2. All six stars are shown to be bound to the Milky Way, and in fact are not even considered high-velocity stars with respect to the Galactic rest frame. Nevertheless, we attempt to characterize their parent Galactic stellar components by simultaneously comparing their element abundance patterns and orbital parameters with those expected from various Galactic stellar components. We find that two of our program stars are typical disk stars. For four stars, even though their kinematic probabilistic membership assignment suggests membership in the Galactic disk, based on their distinct orbit l properties and chemical characteristics, we cannot rule out exotic origins as follows. Two stars may be runaway stars from the Galactic disk. One star has possibly been accreted from a disrupted dwarf galaxy or dynamically heated from a birthplace in the Galactic bulge. The last object may be either a runaway disk star or has been dynamically heated. Spectroscopic follow-up observations with higher resolution for these curious objects will provide a better understanding of their origin.
        4,500원
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