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민영기,진호,이용복 경희대학교 자연과학종합연구원 1995 자연과학논문집 Vol.1 No.-
우리는 경희대 천문대의 76 cm 망원경에 CCD 측광 카메라와 UBV 필터를 부착하여 접촉 쌍성계인 AB Andromedae를 관측했다. 이 관측 결과로 부터 광도곡선과 극심시각을 구하였다. 광도곡선에 나타난 특징의 하나로 일반적인 W형 접촉상성계가 갖는 광도곡선의 비대칭성과 극심 및 극대시의 광도 변화폭이 크게 나타나고 있음을 알아냈다. We observed the contact binary system, AB Andromedae with the 76-cm reflector of Kyung Hee University Observatory equipped with a CCD camera and UBV filters. We derived the light curve and a primary minimum time. The light curve shows an asymmetric feature and fluctuations of brightness at around the primary and the secondary minima which are the typical characteristics of W-type contact binary systems.
The Relationship between Molecular Column Density and Visual Extinction in Dark Clouds
Minn, Y. K. 경희대학교 자연과학종합연구원 2001 자연과학논문집 Vol.7 No.-
By comparing the molecular observational data with the visual extinction in dark clouds, we derived the representative relations between the molecular column density and the visual extinction for the molecules ^(13)CO C^(18)O C^(17)O OH CH CS,H_(2)CO and HCO^(-). The molecular column densities general11 have positive linear relations with the visual extinction. The column density of ^(13)CO has the highest ratio of increase with the extinction while that of HCO^(-) has the lowest ratio of increase. The thresholds of visual extinction for the detection of molecules range from 0 4 mag for HCO^(-) to 1 9 mag for both C^(18)O and C^(17)O.
DISTRIBUTION AND KINEMATICS OF FORMALDEHYDE IN DARK CLOUDS IN M17 AND NGC 2024
MINN Y. K.,LEE Y. B. The Korean Astronomical Society 1994 Journal of The Korean Astronomical Society Vol.27 No.1
The 4.8GHz formaldehyde absorption line in the dark clouds in M17 and NGC 2024 regions has been mapped. In both nebulae, we detected two $H_2CO$ line components. In M17, the 24km $S^{-1}$ cloud is closely associated with the HII region located in front of the radio continuum source, and the 19km $S^{-1}$ cloud is associated with the visual dark clouds with a larger extent which are closer to us. The 19km $S^{-1}$ cloud has a mass motion approaching to the HII region. In both clouds, a velocity gradient from the north-east to the south-west directions is observed. The linewidth has no variation indicating no collapsing motion. In NGC 2024, the 9km $S^{-1}$ feature is extended along the dark bar in front of the bright nebula and a weak second component at 13km $S^{-1}$ is confined to the immediate vicinity of the radio source. Indications are that the 9km $S^{-1}$ cloud is physically associated with the dark bar and the 13km $S^{-1}$ cloud is located behind the radio source. The angular extent, the column density, and the total mass of the clouds are derived. The radial velocities of other molecular lines observed in these clouds are compared.
CHEMICAL EVOLUTION OF INTERSTELLAR CLOUDS AND VARIATIONS OF MOLECULAR ABUNDANCES
Minn, Y.K. The Korean Astronomical Society 1980 Journal of The Korean Astronomical Society Vol.13 No.1
The abundances of simple molecules are examined in terms of the time-dependent cloud evolution. The formation and destruction mechanisms of $H_2CO$ are reviewed. The average value of the fractional abundance of $H_2CO$ is derived to be in the range of $10^{-10}\;to\;5{\times}10^{-9}$. This is comparable to the observed values. The expected variations of the molecules formed from or destroyed by CO, CI, and $C^+$ whose abundances depend on the evolutionary state of the cloud are discussed.
DISTRIBUTION OF $H_2CO$, CO, AND EXTINCTION IN THE DARK CLOUD B5
MINN Y. K.,LEE Y. B.,GREENBERG J. M. The Korean Astronomical Society 1996 Journal of The Korean Astronomical Society Vol.29 No.suppl1
We have made observations of the dark cloud, B5 in the transitions of $H_2CO$, J = $1_{10} {\leftarrow} 1_{11}$, and $2_{12} {\to} 1_{11}$. We compared the $H_2CO$ result with the observational results of CO and with the visual extinction. There exists an overall correspondence of molecules and extinction. However, a detailed agreement is lacking. We discussed the kinematics and the spatial relationship of molecules and extinction in this cloud.
THE RELATION BETWEEN MOLECULE AND VISUAL EXTINCTION IN DARK CLOUDS
Minn, Y.K. The Korean Astronomical Society 1991 Journal of The Korean Astronomical Society Vol.24 No.2
We have compared the column densities of $H_2CO$, $^{13}CO$, $C^{18}O$, $^{12}CO$, CS, and $HCO^+$ to the visual extinctions derived from star counts in eight dark clouds, L1317, B1, L1551, L1535, L1544, L134, L134N, and B335. We examined the degree of correlation between molecules and extinctions. The contours of $^{13}CO$, $H_2CO$, and CS distributions show an excellent coincidence with those of the visual extinction. Even though the plots of molecule brightness temperature or column density as a function of the visual extinction show a considerable scatter, a good correlation is found between the two quantities. The turnover of the ratios of $^{13}CO$ and $H_2CO$ column densities to the visual extinction at high extinctions observed in several clouds is not apparent in this work. The ratios seem to maintain constant values within the range of $A_V$ we studied. The slopes of the relations between the molecule column density and extinction, and the threshold values of extinction for detection of molecules are comparable to the other works. The cause of the slope difference is discussed. We derived, for the first time, the relations of CS and $HCO^+$ column densities and the visual extinction. The ratio of CS column density to extinction is at least two orders of magnitude lower than the mean value for $^{13}CO$, but the threshold for detection of CS is comparable to that of $^{13}CO$. The ratio of the $HCO^+$ column density to extinction is one to two orders of magnitude lower than the mean ratio for $H_2CO$.
STRUCTURE OF $^{13}CO$ EMISSION AND DISTRIBUTION OF IR IN THE DARK CLOUD L1535
LEE YONG BOK,MINN Y. K. The Korean Astronomical Society 1999 天文學論叢 Vol.14 No.2
We have made an extensive mapping of the $^{13}CO$ J=1-0 transition line in the dark cloud L1535. We also constructed the $100{\mu}m$ IRAS map in the region. We found a semi-detached cloud component of $^{13}CO$ in the northeast direction of the $^{13}CO$ main cloud which forms a dumbbell-like structure. This additional component with an angular size of $20'\times16'$ has not been observed before in any molecular surveys of the cloud. The IRAS map shows a similar structure with two intensity peaks whose positions coincide with those of the $^{13}CO$ clouds.
Kim, S.H.,Chang, W.S.,Kim, J.P.,Minn, Y.K.,Choi, J.,Chang, J.W.,Kim, T.S.,Park, Y.G.,Chang, J.H. Dustri-Verlag Dr. Karl Feistle 2011 Clinical neuropathology Vol.30 No.6
<P><U>Aims:</U> The stereotactic brain biopsy is an essential diagnostic procedure in modern neurologic patient management. A side-cutting biopsy needle is one of the most widely used needle types. Recently we found a characteristic tissue artifact named “peripheral compressing artifact” in the brain tissues biopsied using a side-cutting needle of Leksell’s system. We investigate prevalence, possible cause and its clinical implication of this type of artifact. <U>Materials and methods:</U> We examined the biopsies from 80 patients (44 cases of gliomas, 13 lymphomas, 7 germ cell tumors, 2 other tumors, 1 metastatic carcinoma, 4 non-tumorous conditions such as demyelinating disease and 8 non-diagnostic) in the stereotactic biopsy group with a suspected brain tumor, who underwent a stereotactic brain biopsy using side-cutting needle of Leksell’s system. We also evaluated 16 cases of open brain biopsies without Leksell’s system as a control group. <U>Results:</U> The artifact is a semi-circular or band-like tissue compression in the periphery of the biopsied tissue. This artifact was found in 30 (37.5%) out of 80 cases and 57 (11.9%) out of 477 biopsied pieces. It might be produced during rotating of the inner cannula of the biopsy needle. Histologically, it might be misinterpreted as “hypercellular”, “spindle”, “well circumscribed”, or rarely as “pseudopalisading” especially in glioma. <U>Conclusions:</U> Awareness of this artifact would help making the appropriate pathological diagnosis for glioma. </P>