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        검색결과 9,514

        6983.
        1997.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate the velocity distribution of dark matter in the disk of a galaxy like the Milky Way at the solar radius. Using N-body simulations with the total mass and z-component of angular momentum conserved, we calculate the response of a dissipationless dark matter galactic halo during the dissipational collapse of the baryonic matter in spiral galaxy formation. The initial distribution of dark matter and baryonic particles is assumed to be a homogeneous mixture based on a King model. The baryonic matter is assumed to contract, forming the final luminous components of the galaxy, namely the disk and, in some cases, a bulge and central point. Both slow and fast growth of the luminous components are considered. We find that the velocity distribution of dark matter particles in a reference frame rotating slowly about the galaxy center in the plane of the disk is similar to a Maxwellian, but it is somewhat boxier, being flatter at the peak and truncated in the tails of the distribution. We tabulate parameters for the best-fitting Maxwellian and modified-Maxwellian distributions. There is no significant difference between slow collapse and fast collapse for all these results. We were unable to detect any effect of disk formation on the z-dependence of the dark matter density distribution.
        4,300원
        6984.
        1997.06 구독 인증기관·개인회원 무료
        The effect of alloying mode and porosity on the axial tension-tension fatigue behavior of a P/M steel of nominal composition Fe-4w/o Ni-1.5w/o Cu-O.5w/o Mo-O.5w/o C has been evaluated. Alloying modes utilized were elemental powder mixing, partial alloying(distaloy) and prealloying by water atomization; in each case the carbon was introduced as graphite prior to sintering. Powder compacts were sintered(/30 min.) in 7Sv/o /25v/o to densities in the range 6.77-7.2 g/. The dependence of fatigue limit response on alloying mode and porosity was interpreted in terms of the constituent phases and the pore and fracture morphologies associated with the three alloying modes. For the same nominal composition, the three alloying modes resulted in different sintered microstructures. In the elemental mix alloy and the distaloy, the major constituent was coarse and fine pearlite, with regions of Ni-rich ferrite, Ni-rich martensite and Ni-rich areas. In contrast, the prealloy consisted primarily of martensite by with some Ni-rich areas. From an examination of the fracture surfaces following fatigue testing it was concluded that essentially all of the fracture surfaces exhibited dimpled rupture, characteristic of tensile overload. Thus, the extent of growth of any fatigue cracks prior to overload was small. The stress amplitude for the three alloying modes at 2x was used for the comparison of fatigue strengths. For load cycles <3x, the prealloy exhibited optimum fatigue response followed by the distaloy and elemental mix alloy, respectively. At load cycles >2x, similar fatigue limits were exhibited by the three alloys. It was concluded that fatigue cracks propagate primarily through pores, rather than through the constituent phases of the microstructure. A decrease in pore SIze improved the S-N behavior of the sintered steel.
        6986.
        1997.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        4,000원
        6987.
        1997.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        9,200원
        6990.
        1997.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        버섯 재배지에 있어서 주요 해충인 Sciarid fly(Lycoriella sp.)의 생활사와 발육단계별 특성을 조사하였다. 버섯 파리는 팽이버섯(Flammulina velutipes) 균사를 먹이로 공급하고 , 555% 습도, 16L:8D 조건의 항온기에서 누대 사육하였다. 버섯 파리의 알은 직경 0.17 mm, 길이 0.27 mm의 타원형으로 알 기간은 평균 4일이었다. 1령으로부터 3령까지 유충의 체장은 각각 0.7, 1.5와 4.5 mm이었고, 평균 체중은 각각 1.9, 15.4와 9 93.6 이었다. 4령기 유충의 암컷과 수컷은 체장, 마디 크기 및 처1중에 의해 형태적 특정으로 뚜렷하게 구별 할 수 있었다. 4령유충 암컷의 평균 체장과 제중이 각각 5 mm와 162 이었고 수컷은 체장이 3.5 mm, 체중이 90 으로 조사 되었고, 유충 기간은 암컷이 13.5일, 수컷이 13일이였다. 번데기 기간의 암컷과 수컷의 체장은 각각 3.5와 2.7 mm로 나타났으며 평균 체중은 각각 136 과 65으로 암수간 차이가 현저하였다. 성충은 용화 이후 암컷이 5.5일, 수컷은 5일 경과한 후 우화하였고, 성충 기간은 암컷이 평균 5일 수컷은 7일이었다. 암컷의 체중은 수컷보다 2배 이상 높은 것으로 조사되었고, 교미 후 암컷은 130에서 150개의 알을 버섯 균사 위와 속에 산란하였다. 이상의 결과로, 버섯 파리 암컷과 수컷의 경과 일수는 각각 평균 29일 과 213일로 조사되었다.
        4,000원
        6992.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        6993.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        Large field spectrographs are severely influenced by atmospheric refraction. LAMOST is a large field multi-object spectroscopy telescope with 5° field of view, f/5 focus ratio and 20m focal length. There will be 4000 fibers simultaneous on it's ∮1.75m focal plane. Here we discuss the atmospheric refraction effects on LAMOST in two hands. One is the effect of differential refraction across the field, another is the effect of atmospheric dispersion. According to the calculation, we find that: 1. The largest deviation from center within the field is 4.32" during a 1.5-hour integration at 80° declination. 2. The directions of deviation are complex, so the deviations can't be decreased by rotating the field. We also give out the atmospheric dispersions.
        6994.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        We have constructed a near-infrared imaging camera which is attached to the prime focus of 105cm Schmidt telescope at Kiso Observatory. The camera is equipped with a 1040×1040 PtSi CSD array developed by Mitsubishi Electric Co. The combination of Kiso Schmidt and the array gives a wide field of view of 18.4'×18.4' with a reasonable spatial resolution of 1.06' /pixel. The system performances of the camera have been evaluated through laboratory and observational tests. Low noise, good cosmetics(no defect pixels), and good stability of the camera system show an excellent performance for astronomical use.
        6995.
        1996.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Here we report the results from spectroscopic observations of soloar active regions in the HeI 10830 Å line at the German Vacuum Tower Telescope(VTT) in Tenerife during the August 199:3 International EFR(Emerging Flux Region) Campaign. Four active regions in various stages of their evolution, i.e., NOAA7558, 7560, 7561, and 7562, were ovserved on 10 August 1993. From the observed HeI 10830 Å spectra in these active regions, spectroscopic quantities such as equivalent width(EW), doppler shift, doppler width, etc., were derived(see Figure l(a)) and the correlation between them were studied(see Figure l(b)). Our main results are as follows: (I)In NOAA7562, which is a young and evolving EFR, the EW is large, while it is small around a simple and roundish spot of NOAA7558. (2)In these active regions, redshift in the 10830 line is dominant when the EW is larger. (3)As the doppler width increases, the line tends to shift redward. (4)When the EW is smaller, it seems to exist another component which have dynamic characteristics different from the redshifting component. In NOAA7560 and NOAA7561, regions which have several small spots, the values of the EW are intermediate. Results (2) and (3) may suggest the possible existence of downflow above active regions, if the HeI 10830 Å line is formed in the upper chromopshere, and it is consistent with the earlyer result from the SMM extreme-ultraviolet observation by Klimchuk(1987, Astrophys. J., 323, 368) (to be submitted. to Astronomy and Astrophysics; an extended abstract)
        3,000원
        6996.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        Using the data on the occurrences of the Ho: and soft X-ray flares for the time interval of January 1, 1986-May :31, 1994, we have studied the middle term(30-300days) pericities of the solar flare production during the activity cycle 22. Power analysis of the time seies of daily Hα flare index in the northern hemisphere shows prominent periodicities at 220, 120, 109, and 92 days(see Figures l(a) and l(b)), while in the southern hemisphere, those at 267, 213, 183, 167, and 107 days are apparent, though their peaks are not so distint as those in the northern hemisphere. Periodogram of daily soft X-ray flare index also reveal the periodicities at 279, 205, 164, 117, and 91 days in the northern hemisphere, and at 266, 220, 199, 162, 120, and 100 days in the southern hemisphere. Howeer, the 155-day periodicity reported for the earlier cycles, 19, 20, and 21, could not be confirmed in our analysis. to be submitted to Solar Physics; an extended abstract.
        6997.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        Nearly simultaneous observations for 28SiO v=0, 1, 2, J =3-2 transitions in 39 late-type stars have been carried out in February 1995 and 1996 with the 14 m radio telescope at Taeduk Radio Astronomy Observatory (TRAO). Observations for 28SiO v=0, 1, 2, J=2-1 lines in the same objects have been also carried out in March 1995 and March-April 1996. The detection rate of 28SiO v=l, J=3-2 line for the 28SiO v=l, J=2-1 sources was 59%. Seventeen new detections in the 28SiO v=l, J=3-2 transition and 4 new detections in the 28SiO v=2, J=3-2 transition have been reported including the intensity ratios within the vibrational ladders and rotational states.
        6998.
        1996.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서 필자는 예이츠의 초기시에 나타난 신화를 가면으로 보고, 그가 왜 초기시에서 신화의 인물들을 자신의 가면으로 사용하는지를 라깡의 ‘구술치료’를 원용하여 밝혀 보고자 하였다. 본 논문에서는 특히 아일랜드 신화가 투영된 시들을 분석하였다. 예이츠의 신화 사용에서 주목할 점은 그가 신화를 변용하였다는 것이다. 이것은 곧 시인이 신화를 변용함으로써 자신의 어떤 의도를 거기에 투영하였다는 것이다. 초기시에 나오는 신화의 인물들은 세 부류로 나뉘어진다: Fergus and King Goll, Aengus and Oisin, and Cuchulain. 퍼거스와 골왕의 신화는 젊은 시인의 시적 추구의 한 모습을 나타내며, 앵거스와 어신의 신화는 모드 곤과의 사랑의 드라마를 투영한 것이며, 쿠훌린은 시인이 바라는 이상적인 영웅상을 그린 것이다. 예이츠는 이러한 신화의 이야기를 통해 현실에서 바라지만 쉽게 이룰 수 없는 욕망들을 투영하고자 한 것이다. ‘Unity of being’은 예이츠가 평생동안 추구한 화두이다. 초기시에 나타난 신화의 인물들도 모두 이 주제로 통합될 수 있다. 시인은 이상적인 자아와 실제의 자아 사이에서 끊임없이 갈등하였다. 식민지 조국에 대한 갈등, 이루어지지 않는 사랑에 대한 갈등을 겪어야 했다. 현실에서의 좌절을 극복하고 결핍을 채우기 위해 시인이 택한 것은 가면이었다. 이를 통해 시인은 자신의 바라는 바를 충족할 수 있었을 것이다. 그러나 시인이 바라는 가면을 쓴다고 할지라도, 실제의 자아와 이상적인 자아와의 틈은 영원히 채워질 수 없다. 끊임없이 다다르려고 할 뿐 쉽게 이를 수 없는 예이츠의 장미와 같다. 그러나 이러한 욕망과 결핍의 드라마 또는 비극성이 시인에게는 오히려 창조의 힘이 된다. 그렇기에 시인이 택하는 가면은 완전한 해결책은 아니었을지라도, 최선의 해결책인 것이다. 그런 의미에서 예이츠의 초기시에 등장하는 가면들은 보다 나은 reality 또는 unity of being에 이르고자 하는 시인의 시적 추구의 도구인 것이다.
        6,900원
        6999.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        The imaging spectroscopic observations of the Magellanic irregular galaxy NGC 4449 were made to show the detailed kinematic structure of the galaxy. Many filamentary structures and Several bubble-like structures are recognized in a 3D data cube of H$\alpha$ 수식 이미지 emission line. Velocity field shows the kpc-scale mosaic structure and counter- rotation of ionized gas.
        7000.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        We have started multi-color imaging program of nearby galaxies since last year and present preliminary result here. We selected 12 nearby galaxies classfied from E to Sab type and observed in BVRIJHK' bands. Photomtric parameters such as isophotal diameter, axial ratio, isophotal magnitude were measured and observed colors were compared with theoritical model. We find a standard evolution model agrees well with observed results.