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        검색결과 140

        22.
        2017.04 구독 인증기관·개인회원 무료
        Ochratoxin A, which is frequently detected in cereals and infant diets worldwidely, is a mycotoxin to damage mainly the kidney and liver. Because ochratoxin A is highly thermostable compound. it is necessary to study ways of reducing level of ochratoxin A by controling processing steps. However, food processes, including extrusion, expansion, roasting, and steam cooking, which are used in order to mitigate the contents of ochratoxin A, are known to produce polycyclic aromatic hydrocarbons, which are generated from radicals decomposed by pyrolysis. Therefore, this study analyzed the levels of 4 polycyclic aromatic hydrocarbons, benz (a) anthracene, chrysene, benzo (b) fluoranthene and benzo (a) pyrene in rice-based products made in high pressure and heating process. Rice samples were finely ground, and homogenized samples were alkaline treatement with 1 M KOH/EtOH and extracted with liquid-liquid extraction method using n-hexane. The extracted solution was pretreated with a silica cartridge. The purified solution was dried with nitrogen gas and dissolved in 1 mL of dichloromethane and injected into GC/MSD. We had overall recoveries for 4 polycyclic aromatic hydrocarbons spiked into rice samples ranging from 92.8 to 110.2%. The limit of quantitations of benz (a) anthracene, chrysene, benzo (b) fluoranthene and benzo (a) pyrene in rice-based product were 0.19 ng/g, 0.38 ng/g, 0.51 ng/g, and 0.31 ng/g, respectively. However, these 4 polycyclic aromatic hydrocarbons in all processed rice samples were not detected.
        23.
        2016.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present analyses of 1250 variable sources identi ed in a 20 square degree eld toward NGC 2784 by the KMTNet Supernova Program. We categorize the variable sources into three groups based on their B-band variability. The rst group consists of 31 high variability sources with their B- band RMS variability greater than 0.3 magnitudes. The second group of medium variability contains 265 sources with RMS variability between 0.05 and 0.3 magnitudes. The remaining 951 sources belong to the third group of low variability with an RMS variability smaller than 0.05 magnitudes. Of the entire 1250 sources, 4 clearly show periods of variability greater than 100 days, while the rest have periods shorter than 51 days or no reliable periods. The majority of the sources show either rather irregular variability or short periods faster than 2 days. Most of the sources with reliable period determination between 2 and 51 days belong to the low-variability group, although a few belong to the medium-variability group. All the variable sources with periods longer than 35 days appear to be very red with B􀀀V > 1.5 and V 􀀀I > 2.1 magnitudes. We classify candidates of 51 Cepheids, 17 semi-regular variables, 3 Mira types, 2 RV(B) Tauri stars, 26 eclipsing binary systems and 1 active galactic nucleus. The majority of long-term variables in our sample belong to either Mira or semi-regular types, indicating that long-term variability may be more prominent in post-main sequence phases of late-type stars. The depth of the eclipsing dips of the 26 candidates for eclipsing binaries is equivalent to 0.61 as the average relative size of the two stars in the binary system. Our results illustrate the power of the KMTNet Supernova Program for future studies of variable objects.
        4,800원
        27.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A large-scale neutral hydrogen (H i) ring serendipitously found in the Leo I galaxy group is 200 kpc in diameter with MHi ~ 1:67 X 109M⊙, unique in size in the Local Universe. It is still under debate where this Hi ring originated - whether it has formed out of the gas remaining after the formation of a galaxy group (primordial origin) or been stripped during galaxy-galaxy interactions (tidal origin). We are investigating the optical and Hi gas properties of the dwarf galaxies located within the gas ring in order to probe its formation mechanism. In this work, we present the photometric properties of the dwarfs inside the ring using the CFHT MegaCam u*, g', r' and i'-band data. We discuss the origin of the gas ring based on the stellar age and metal abundance of dwarf galaxies contained within it.
        3,000원
        28.
        2015.09 KCI 등재 구독 인증기관·개인회원 무료
        We present population synthesis models for the calcium II triplet (CaT), currently the most popular metallicity indicator, based on high-resolution empirical spectral energy distributions (SEDs). Our new CaT models, based on empirical SEDs, show a linear correlation below [Fe/H] ~ -0.5, but the linear relation breaks down in the metal-rich regime by converging to the same equivalent width. This relation shows good agreement with the observed CaT of globular clusters (GCs) in NGC 1407 and the Milky Way. However, a model based on theoretical SEDs does not show this feature of the CaT and fails to reproduce observed GCs in the metal-rich regime. This linear relation may cause inaccurate metallicity determination for metal-rich stellar populations. We have also con rmed that the effect of horizontal- branch stars on the CaT is almost negligible in models based on both empirical and theoretical SEDs. Our new empirical model may explain the difference between the color distributions and CaT distributions of GCs in various early-type galaxies. Based on our model, we claim that the CaT is not a good metallicity indicator for simple stellar populations in the metal-rich regime.
        30.
        2014.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        차 (Tea)는 네팔을 포함한 남아시아의 주요 농산물 수출품목 중에 하나이다. 네팔의 차 생산은 150년 전에 시작되었지만, 상업적인 생산 규모는 발전 가능성이 있음에도 불구하고초창기 모습 그대로이다. 차 생산에서 우위를 차지하고 있는인도, 스리랑카, 방글라데시와 같이 네팔은 좋은 품질의 차를생산할 수 있는 큰 잠재력을 가지고 있다. 그리고 현재 차 산업의 선도자로 남아시아 국가의 잠재력을 강화하기 위해 남아시아지역협력연합 (South Asian Association for the RegionalCooperation, SAARC)은 각 회원국의 National Tea board가차 산업을 육성할 수 있도록 지원하기 위하여 차 위원회를 설립할 예정이다. 이러한 남아시아지역협력연합의 차 위원회 설립에 맞추어 본 연구는 남아시아 차 산업에서 부각되고 있는네팔의 차 생산과 소비, 그리고 수출 경향을 다른 남아시아국가와 비교하여 분석하였다. 남아시아는 전세계 차 생산량의약 1/3를 생산하고 있으며, 대표적인 차 생산국가는 인도, 스리랑카, 방글라데시, 네팔이다. 남아시아 중에서 네팔은 연간약 1만8천톤의 차를 생산하고 있으며, 최근 20여년간(1994~2012) 차 생산량이 약 100배(196톤→18,309톤) 가까이 급증하고 있다. 네팔의 차 산업은 수출증대를 통해 외화획득과 경제발전에 기여할 뿐만 아니라 차 생산과 가공산업에참여하는 농가와 농촌여성의 고용창출 측면에서 매우 중요한역할을 담당하고 있다.
        4,000원
        31.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Isotropic pitch fibers were stabilized and carbonized for preparing carbon fibers. To optimize the duration and temperature during the stabilization process, a thermogravimetric analysis was conducted. Stabilized fibers were carbonized at 1000, 1500, and 2000℃ in a furnace under a nitrogen atmosphere. An elemental analysis confirmed that the carbon content increased with an increase in the carbonization temperature. Although short graphitic-like layers were observed with carbon fibers heat-treated at 1500 and 2000℃, Raman spectroscopy and X-ray diffraction revealed no significant effect of the carbonization temperature on the crystalline structure of the carbon fibers, indicating the limit of developing an ordered structure of isotropic pitch-based carbon fibers. The electrical conductivity of the carbonized fiber reached 3.9×10⁴S/m with the carbonization temperature increasing to 2000℃ using a four-point method.
        4,000원
        32.
        2013.06 구독 인증기관 무료, 개인회원 유료
        The cultivation methods of Acanthopanax in Korea need to be optimized. Hence, this study investigated the effect of different fertilizer ratios and planting dates on the growth and acanthoside D content of two (2) Acanthopanax species. The current recommended fertilizer rate of 10.5-8.5-8.5 kg/ha- (N-P2O5-K2O, respectively) produced the best plant growth of Acanthopanax. For the first year, the acanthoside D content resulting from the 2P (2x phosphate) rate was higher than that from the other fertilizer ratios, yet there were no significant differences resulting from the various treatments for either Acanthopanax divaricatus or Acanthopanax koreanum. Similarly, for the second year, there were no significant differences in the acanthoside D content resulting from the various fertilizer ratios, although for both species the acanthoside D content resulting from the 2P rate was slightly higher than that from the other treatments. Therefore, the results indicated that doubling the amount of phosphate increased the acanthoside D content. Plus, the optimum planting date with respect to growth and productivity for Acanthopanax divaricatus was identified as April 15. The cultivation methods of Acanthopanax in Korea need to be optimized. Hence, this study investigated the effect of different fertilizer ratios and planting dates on the growth and acanthoside D content of two (2) Acanthopanax species. The current recommended fertilizer rate of 10.5-8.5-8.5 kg/ha- (N-P2O5-K2O, respectively) produced the best plant growth of Acanthopanax. For the first year, the acanthoside D content resulting from the 2P (2x phosphate) rate was higher than that from the other fertilizer ratios, yet there were no significant differences resulting from the various treatments for either Acanthopanax divaricatus or Acanthopanax koreanum. Similarly, for the second year, there were no significant differences in the acanthoside D content resulting from the various fertilizer ratios, although for both species the acanthoside D content resulting from the 2P rate was slightly higher than that from the other treatments. Therefore, the results indicated that doubling the amount of phosphate increased the acanthoside D content. Plus, the optimum planting date with respect to growth and productivity for Acanthopanax divaricatus was identified as April 15. The cultivation methods of Acanthopanax in Korea need to be optimized. Hence, this study investigated the effect of different fertilizer ratios and planting dates on the growth and acanthoside D content of two (2) Acanthopanax species. The current recommended fertilizer rate of 10.5-8.5-8.5 kg/ha- (N-P2O5-K2O, respectively) produced the best plant growth of Acanthopanax. For the first year, the acanthoside D content resulting from the 2P (2x phosphate) rate was higher than that from the other fertilizer ratios, yet there were no significant differences resulting from the various treatments for either Acanthopanax divaricatus or Acanthopanax koreanum. Similarly, for the second year, there were no significant differences in the acanthoside D content resulting from the various fertilizer ratios, although for both species the acanthoside D content resulting from the 2P rate was slightly higher than that from the other treatments. Therefore, the results indicated that doubling the amount of phosphate increased the acanthoside D content. Plus, the optimum planting date with respect to growth and productivity for Acanthopanax divaricatus was identified as April 15. The cultivation methods of Acanthopanax in Korea need to be optimized. Hence, this study investigated the effect of different fertilizer ratios and planting dates on the growth and acanthoside D content of two (2) Acanthopanax species. The current recommended fertilizer rate of 10.5-8.5-8.5 kg/ha- (N-P2O5-K2O, respectively) produced the best plant growth of Acanthopanax. For the first year, the acanthoside D content resulting from the 2P (2x phosphate) rate was higher than that from the other fertilizer ratios, yet there were no significant differences resulting from the various treatments for either Acanthopanax divaricatus or Acanthopanax koreanum. Similarly, for the second year, there were no significant differences in the acanthoside D content resulting from the various fertilizer ratios, although for both species the acanthoside D content resulting from the 2P rate was slightly higher than that from the other treatments. Therefore, the results indicated that doubling the amount of phosphate increased the acanthoside D content. Plus, the optimum planting date with respect to growth and productivity for Acanthopanax divaricatus was identified as April 15. The cultivation methods of Acanthopanax in Korea need to be optimized. Hence, this study investigated the effect of different fertilizer ratios and planting dates on the growth and acanthoside D content of two (2) Acanthopanax species. The current recommended fertilizer rate of 10.5-8.5-8.5 kg/ha- (N-P2O5-K2O, respectively) produced the best plant growth of Acanthopanax. For the first year, the acanthoside D content resulting from the 2P (2x phosphate) rate was higher than that from the other fertilizer ratios, yet there were no significant differences resulting from the various treatments for either Acanthopanax divaricatus or Acanthopanax koreanum. Similarly, for the second year, there were no significant differences in the acanthoside D content resulting from the various fertilizer ratios, although for both species the acanthoside D content resulting from the 2P rate was slightly higher than that from the other treatments. Therefore, the results indicated that doubling the amount of phosphate increased the acanthoside D content. Plus, the optimum planting date with respect to growth and productivity for Acanthopanax divaricatus was identified as April 15.
        4,000원
        35.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, reduced graphene oxide/polyimide (r-GO/PI) composite films, which showed significant enhancement in their electrical conductivity, were successfully fabricated. GO was prepared from graphite using a modified Hummers method. The GO was used as a nanofiller material for the preparation of r-GO/PI composites by in-situ polymerization. An addition of 20 wt% of GO led to a significant decrease in the volume resistivity of composite films by less than nine orders of magnitude compared to that of pure PI films due to the electrical percolation networks of reduced GO created during imidization within the films. A tensile test indicated that the Young's modulus of the r-GO/PI composite film containing 20 wt% GO increased drastically from 2.3 GPa to 4.4 GPa, which was an improvement of approximately 84% compared to that of pure PI film. In addition, the corresponding tensile strength was found to have decreased only by 12%, from 113 MPa to 99 MPa.
        4,000원
        36.
        2012.10 구독 인증기관·개인회원 무료
        We reviewed the Korean species belonging to the genus Hemicrepidius. Of the previously recorded five species, the specimens known as H. (s. str.) secessus secessus (Candèze, 1873) are confirmed as the misidentification of H. oblongus (Solsky, 1870). The status of H. (s. str.) secessus hallaensis Kishii 2002 is suggested to be raised to species level. We also propose three new species, H. (s. str.) sp1 nov., H. (s. str.) sp2 nov., H. (Miwacrepidius) sp1 nov. from Korea. In Hemicrepidius sensu strito, molecular approaches based on the species recognized from Korea, Russia, and Japan using COI and 16S rRNA genes strongly support that all Korean species and the Russian specimens of H. oblongus are clustered into a monophyletic group, whereas Japanese species might be early and independently divided from the former.
        37.
        2012.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
         ,  , Pseudanostirus ecarinatus (Stepanov, 1930) is recognized for the first time in Korea. A redescription and illustrations of the species are presented based on a single male specimen collected from Mt. Bangtae Gangwon-do. We also provide diagnostic characteristics of the genus, which clearly separate it from other closely related genera, Calambus Thomson, 1859 and Anostrius Thomson, 1859.
        3,000원
        38.
        2012.05 구독 인증기관·개인회원 무료
        We reviewed the Korean species belonging to the Tribe Dendometrini. Of the previously recorded five species in Korea, Athousius humeralis (Miwa, 1927) and Limoniscus rufipennis (Lewis, 1894) are confirmed as the misidentification of Ampedus basalis (Mennerheim, 1852) and Corymbitodes sp., respectively. It is suggested to exclude these species in the Korean fauna. In addition, the records of Limonius eximius (Lewis, 1874) and Limoniscus vittatus (Candèze, 1873) are also questionable since no specimens available in this study. We actually examined three species throughout this study. Limoniscus kraatzi ((Candèze, 1879) is recognized as the mostly abundant species in the Korean fauna. A new species, Cidnopus nigronitidus sp. nov. and a new record of Limoius scutellaris (Dolin, 2003) comb. nov. are recognized in Korea.
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