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        검색결과 5

        1.
        1995.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present UBVRI CCD photometry of the Type Ie supernova SN 19941 in M51 which was discovered on April 2, 1994 (UT). UBVRI CCD photometry of SN 1994 I were obtained for the period of the first two months from April 4, 1994, using the Seoul National University Observatory 60 cm telescope. The light curves of SN 19941 show several interesting features: (a) SN 19941 reaches the maximum brightness at B-band on April 8.23 (B = 13.68 mag), at V-band on April 9.10 (V = 12.89 mag), and at I-band on April 10.32 (I = 12.48 mag); (b) The light curves around the maximum brightness are much narrower than those of other types of supernovae; (c) The light curves after the peak decline more steeply than those of other types of supernovae; and (d) The colors get redder from (V-R) ≈ 0.2 mag ((V - I) ≈ 0.3 mag, (B - V) ≈ 0.7 mag) on April 4 to (V-R)≈ 0.6 mag ((V-1) ≈0.9 mag, (B-V) ≈ 1.3 mag) on April 18. Afterwards (V - R) colors get bluer slightly (by ~0.005 mag/day), while (V-I) colors stay almost constant around (V-1) ≈ 1.0 mag. The color at the maximum brightness is (B-V)=0.9 mag, which is ~1 mag redder than the mean color of typical Type la supernovae at the maximum brightness. The light curves of SN 1994I are similar to those of the Type Ie supernova SN 1962L in NGC 1073. Adopting the distance modulus of (m-M)0 = 29.2 mag and the reddening of E(B - V) = 0.45 mag [Iwamoto et al. 1994, preprint for ApJ], we derive absolute magnitudes at the maximum brightness of SN 1994I, Mv(max) = -17.7 mag and MB(max) = -17.4 mag. This result shows that SN 1994I was ~2 mag fainter at the maximum brightness compared with typical Type Ia supernovae. A narrower peak and faster decline after the maximum in the light curve of SN 1994I compared with other types of supernovae indicate that the progenitor of SN 1994I might be a lower mass star compared with those of other types of supernovae.
        4,500원
        2.
        1994.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The BVR CCD photometry was performed for the globular cluster M13 down to V=19m over the region from the center to the west 13 arcmin and the CMD of M13 is investigated. The major photometric error in the crowded field which is due to the variation in the sky background was corrected by the median filtering method and the direct sky method. Some characteristics of the CMD of M13 obtained in the present study are as follows: Firstly, the distribution of stars on the CMD is well consistent with the mean lines of Sandage(1970) along the red giant branch(RGB), horizontal branch(HB) and asymtotic giant branch(AGB). Secondly, some gaps exists along the RGB and blue horizontal branch(BHB). Thirdly, the UV-bright stars are more concentrated at the inner region of the cluster.
        4,600원
        3.
        2012.12 KCI 등재 서비스 종료(열람 제한)
        리퀴리티게닌과 이소리퀴리티게닌은 감초의 주요 플라보노이드 성분이다. 이들 플라보노이드는 수용성 감초추출물과 β-glucosidase를 생성하는 잎새버섯 HB0071 균사체 발효배양을 통하여 생산하였다. 감초추출물 내 리퀴리티게닌과 이소리퀴리티게닌은 잎새버섯 발효배양 동안 현저히 증가하였다. 이 균주의 β-glucosidase의 활성은 배양 96시간을 기준으로 최고 91.5 mU/mL로 확인되었으며, 감초추출발효물로부터 생성된 리퀴리티게닌과 이소리퀴리티게닌의 함량은 HPLC 분석을 통하여 최대 568.5 μg/mL과 89.6 μg/mL로 확인되었다. 본 연구에서는 감초추출물의 잎새버섯 발효 전․후의 시료가 처리된 각질형성세포를 이용하여 자외선 UVB에 조사로 발현된 염증유발인자(COX-2)와 사이토카인(IL-1β, IL-6) 모두 감초추출발효물(FLEx)에서 농도의존적으로 발현이 억제되는 것을 확인하였다. 결론적으로 리퀴리티게닌과 이소리퀴리티게닌의 함량이 증가된 감초추출발효물은 자외선으로부터 손상된 피부 염증반응을 완화시켜줄 것으로 사료된다.