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        검색결과 819

        602.
        2000.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The synthetic methods for high yield of multiwalled carbon nanotube (MWNT) and singlewalled carbon nanotube (SWNT) with high purity by arc discharge have been investigated. MWNTs were synthesized under different pressures of helium and the gas mixture of argon and hydrogen. Relatively high pressure of 300-400 torr was required for high yield MWNTs synthesis at low bias voltage of about 20 V and 55 A, whereas low pressure of about 100 torr was required for SWNTs. The introduction of hydrogen gases during the synthesis of MWNTs improved the yield and purity of the samples. The SWNTs were synthesized by the assistance of a small amount of mixture of transition metals, which played as a catalyst during the formation process. The purity and yield of SWNTs were higher at a lower pressure and enhanced by mixing more components of the transition metals.
        4,000원
        603.
        2000.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The international ultraviolet explorer (IUE) spectra of a low dispersion ~6 Å, have been investigated for two Seyfert 1 galaxies, Mrk 335 and NGC 4051, well known for the line variability. The electron densities of broad line region (BLR) of these variable Seyfert 1 galaxies have been derived, which showed a non-linear abrupt variation from 10 8 to 10 10 cm-3 within a month. We also found the excitation (or temperature) changes in the Mrk 335 BLR from the IUE broad line profiles analysis, but no such evidence in the NGC 4051. The large amount of mass inflow activity through the bar or spiral structure of host galaxies, may trigger the density change in BLR and emission line variability for both objects. Mass of the giant black holes appear to be order of 10 7 M⊙ for both variable Seyfert l's.
        4,000원
        605.
        2000.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out to determine a fertilization rate for productivity and nutritive value improvement of silage corn, using two kinds of composts, and to examine the potential possibility of utilization as an organic fertilizer. The experiment was
        4,000원
        611.
        1995.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        담배포장에서 담배나방의 발생은 조식 및 만식 재배구 모두에서 2 또는 3개의 뚜렷한 최성기를 보였다. 반면에 Campoleitis chlorideae는 담배 조식구에서는 담배나방의 두번째 최성기 직후 짧은 기간동안 발생하였으며 만식구에서는 담배나방 유웅이 존재하는 한 발생하였다. 만식구에서의 담배나방 발생은 조식구에서보다 많았다. 4가지 담배 품종중 NC-744에서 담배나방 유충의 발생이 비교적 컸다. 그러나, 기생벌의 발생은 Burley-21과 NC-82에서 많았다. 담배나방 유충의 포장에서의 인위적인 방사 및 재포획법에 의한 결과는 C. chlorideae의 활동은 6월말부터 9월초까지 보였으며 7월초 부터 8월말까지는 비교적 높은 밀도로 발생하였다. C. chlorideae의 담배나방에 대한 생물적방제 수단으로서의 가치평가를 위한 포장내 소규모 케이지 실험결과 방사밀도가 높을수록(암컷 4마리/2 ) 유충기생률이 높고(86.1%) 담배잎의 피해는 감소함을 보였다.(8.7%) 무처리구에서의 담배잎의 피해는 상당히 높았으며(23.2%) 살충제처리구에서 피해가 가장 낮았다.(1.6%)
        4,000원
        613.
        1993.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The premiums on closed-end country funds tend to move in tandem, but do not move together with premiums on domestic closed-end funds. After controlling for foreign maket fundamentals, changes in the stock price of country funds co-move with U.S. market returns, but changes in their net asset values do not. An index of changes in country fund premiums explains cross-sectional stock returns in the U.S. market, particularly for small firms. Collectively, these findings suggest U.S. stock prices are affected by market-wide sentiments which are reflected in closed-end country fund premiums.
        9,300원
        615.
        1992.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        反復혜重올 받는 짧은 I 보 (Beam) 의 慣-비틀림 座때(Lateral-Torsional Buckling) 에 대한 흩윌뼈한 Parametric Study 를 逢行하여 보의 座맴現象올 좀 더 깊이 考흉하고자 한다. 有限한 비틀림햇形의 뒤틀림 (Warping) 이외에 m 少한 맺톨JTft形의 뒤틀립도 고려한 幾何學적 (完全) 非綠形의 一次7ê 보를 껴¥析的 모델 로 사용하고, 또한 金!홉의 周期的뺑性(Cyclic Plasticity) 쌓:tJJ을 보다 잘 나타내기 위해 多빼 週期的뿔性 모 덴올 Consistent Return Mapping Algorithm과 결합시켜 遭用한다. :한ì.ffI때 단방에서 아래와 갇은 여러가지 Parameter Study를 끊行함으로써 反復휴重을 받는 짧은 I 보의 함 -비블립 座며의 -압的 應홈을 ι~.흉한다 : 材料의 降ik~옳度, 降ik플래토 (Yield Plateau) , 뿔形率硬化,U-:tJJ 硬化(Kinematic Hardening) , 웰留應力, 作用倚重의 f.1端中心에 대 한 {f,í ι、率, 作用倚훌의 보 톰面에 대 한 높 이, 作用혜훨의 보 김이방향의 位置, 보 뻐f 面의 置f!{, 作用倚重으로 부터 멀리 떨어진 支持端의 固定度.
        4,600원
        616.
        1992.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Lateral bracing has long been used in design practice to enhance the carrying capacity of the lateral buckling of the beam. Many factors. critically important to lateral bracing performance. do not appear in design formulas. Some of these factors are discussed in this study for the application to short 1 - beams under repeated loadings through parametric studies with an analytical model : the brace 10' cation along the length of the beam. the height of the bracing above the shear center of the beam. and the strength and stiffness of the brace. The parametric studies are carried out using a propped cantilever arrangement. and also using a geometrically (fully) nonlinear beam model for the brace as well as the beam to capture the system buckling. An idealized bracing system is configured to restrain lateral motion. but not rotation. A multiaxial cyclic plasticity model is also implemented to better represent cyclic metal plasticity in con. junction with a consistent return mapping algorithm.
        4,000원
        617.
        1986.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        변색미(變色米) 발생(發生)에 관여(關與)하는 병원균(病原菌)과 해충을 분류동정(分類同定)한 결과(結果) 해충으로는 허리노린재과(科)에 속하는 Leptocorisa oratorius가 우점종(優占種)이었고 노린재과(科)인 Menida varipennis. Stollia ventralis 및 Nezara viridula 등이 관여(關與)하였으며 병원균(病原菌)으로는 Drechslera oryzae. Curvularia lunata, Trichoniella padwickii, Sarocladium oryzae, Alternaria tenuis 및 Fusarium solani 등이 관여(關與)하였다. 병원균(病原菌)과 해충의 복합발생시(複合發生時)에 변색미발생(變色米發生)이 더 심하였고 병원균(病原菌)만의 발생시(發生時)는 변색미(變色米) 발생(發生)에 주로 영향(影響)을 미쳤으며 노린재류만의 발생시(發生時)는 수량감수(收量減收)에 더 큰 영향(影響)을 주었다. 그리고 노린재류에 의한 벼 유숙기간(乳熟期間)의 흡즙(吸汁)은 병원균침입(病原菌侵入)을 조장(助長)하여 벼의 질적(質的) 변화(變化)와 양적(量的) 감소(滅少)에 크게 영향(影響)하였다.
        4,000원
        620.
        2021.08 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This technical paper deals the practical transformation algorithms between several lunar reference frames which will be used for Korea pathfinder lunar orbiter (KPLO) flight operation. Despite of various lunar reference frame definitions already exist, use of a common transformation algorithm while establishing lunar reference frame is very important for all members related to KPLO mission. This is because use of slight different parameters during frame transformation may result significant misleading while reprocessing data based on KPLO flight dynamics. Therefore, details of practical transformation algorithms for the KPLO mission specific lunar reference frames is presented with step by step implementation procedures. Examples of transformation results are also presented to support KPLO flight dynamics data user community which is expected to give practical guidelines while post processing the data as their needs. With this technical paper, common understandings of reference frames that will be used throughout not only the KPLO flight operation but also science data reprocessing can be established. It is expected to eliminate, or at least minimize, unnecessary confusion among all of the KPLO mission members including: Korea Aerospace Research Institute (KARI), National Aeronautics and Space Administration (NASA) as well as other organizations participating in KPLO payload development and operation, or further lunar science community world-wide who are interested in KPLO science data post processing.