• 천문학회보
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• 제42권1호
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• pp.44.1-44.1
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• 2017

The single lens event OGLE-2015-BLG-1482 has been simultaneously observed from two ground-based surveys and from Spitzer. The Spitzer data exhibit finite-source effects due to the passage of the lens close to or directly over the surface of the source star as seen from Spitzer. Thanks to measurements of the microns parallax and the finite-source effect, we find that the lens of OGLE-2015-BLG-1482 is a very low-mass star with the mass $0.10{\pm}0.02M{\odot}$ or a brown dwarf with the mass $55{\pm}9MJ$, which are respectively located at $DLS=0.80{\pm}0.19kpc$ and $DLS=0.54{\pm}0.08kpc$, and thus it is the first isolated low-mass microlens that has been located in the Galactic bulge. The degeneracy between the two solutions is severe. The fundamental reason for the degeneracy is that the finite-source effect is seen only in a single data point from Spitzer and this single data point gives rise to two ${\rho}$ solutions.

• 천문학회보
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• 제36권2호
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• pp.115.1-115.1
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• 2011

We analyzed the line profiles of the planetary nebula (PN) NGC 7009 secured with the Keck I HIES and BOES's spectral data. The 5 positions were taken over the nebular image, 4 points on the bright rim plus 1 point at the central position. The covered spectral wavelength range was $3250{\AA}-8725{\AA}$ in these observations. We decomposed the lines of HI, HeI, HeII, CII, NIII, [ClIII], [NII], [OII], [OIII], [SII], [SIII], [ClIII], and [ArIII] using the IRAF and StarLink/Dipso. After correcting the Earth's movement and the PN's radial velocities, -48.6 & -48.9 km/s, respectively, for the Keck & BOES, we produced the line profiles in a velocity scale. The zero velocity at each line profile clearly indicates which part of the components is approaching or receding, giving a general information of the kinematical structure. Almost all of the low-to-medium excitation lines, such as [NII], [SII], [O III], and [ArIII], secured at the central position and four positions along the major & minor axes, showed 3 components, double peak + a wide wing component, suggesting the fast outflow structures are present. The overall geometry is a prolate shell which also has a fainter outer shell in the halo zone, but there appears to be some peculiar sub-structures inside the main shell. The high excitation He I, HeII, NIII lines which might be formed close to the inner boundary of the shell show unusual features, completely different from the other lines. The HeII and these high excitation lines may be indicative of a relative recent fast outflow from the central star and the permitted lines such as NIII might be affected by the innermost structure. We discuss a possible presence of a jet-like fast outflow structure in an out-flow axis different from the main axis of the spheroid shell.

• 천문학회보
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• 제36권1호
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• pp.27.1-27.1
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• 2011

We obtained the spectra of 93 Planet host stars and 73 normal field stars in F, G, K type using BOES at BOAO. We measured the equivalent width of Fe and 25 elements lines using the automatic EW measurement program, TAME(Tools for Automatic Measurement of Equivalent-widths) and estimated the elemental abundances by synth and abfind driver of MOOG code. Since the absence of planets in the normal field stars cannot be "completely" proved, this work focused on the chemical abundances and planet properties of planet host stars, which have the massive planets close to the parent star relatively. We carried out an investigation for the difference of abundances between stars with "Hot Jupiter" and normal field stars with no known planets. We examined the chemical composition of 25 elements, such as C, N, O, S, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu by EW measurements, and the S abundances were estimated using synthetic spectrum. We have found that [Mg/Fe] and [Al/Fe] for planet host stars have lower limit comparing with those of comparison stars, and [Ca/Fe] of host star with Neptunian planets is relatively lower than the other host stars with massive planets. We have performed the Kolmogorov-Smirnov test, and examined the ratio of planet host stars to all stars for each bin of [X/H]. As a result, we noted that the O, Si, and Ca abfor undances are strongly related with the presence of planets.

• 대한기계학회논문집B
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• 제37권2호
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• pp.103-109
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• 2013

본 연구에서는 초소형 가스터빈 연소기에서의 수소/공기 연소에 대한 수치해석을 연소기 입구에서의 공급 유량 및 유체의 수소/공기 혼합비 변화에 대하여 수행하였다. 수치해석은 상용화 프로그램인 STAR-CCM 을 이용하였다. 유체의 공급 유량의 변화는 연소기 내 화염의 위치와 온도, 입구와 출구의 압력비 등에 상당한 영향을 주었다. 유체의 공급 유량이 증가할 때, 연소기 내의 화염은 점점 출구 방향으로 위치하였고, 화염의 온도 및 입구와 출구의 압력비는 단조적으로 증가하였다. 유체의 수소/공기 혼합비 변화는 화염의 위치에는 큰 영향을 주지 않았고, 이론공연 상태에서 연소실 내에 가장 높은 화염온도를 가졌다.

• 한국의류학회지
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• 제28권2호
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• pp.212-223
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• 2004

The purpose of this study is 1) to identify Chinese environment for investment and apparel market, 2) to analyze the current situations of Korean fashion brands＇entry to Chinese market, 3) to analyze the marketing strategies to China according to product category, and 4) to identify merits and problems of Chinese market. For data collection, secondary resources were collected, and the telephone interview with merchandisers were implemented with brand managers. Twenty-one fashion brands were included for the study. Results of the study were as followed： 1) China was a big potential apparel market due to its rapid economic growth. Apparel purchase behavior and clothing preference of Chinese consumers were various by regional groups. 2) The motives of entry to China were to competition in domestic markets, saving raw material cost. The entry modes to China were direct export, license and regional manufacturing system. 3) Marketing strategies were to pursue high quality branding, high pricing and placing strategies with high-class department stores. Also star marketing were used with ＂Han Rue＂. Also various promotion strategies were implemented such as fashion show and unique VMD. 4) The merits of Chinese market were high potential market for export, close proximity, cultural similarity and Han-Ryu syndrome. Problems of Chinese market for export were lack of experts on Chinese market, fierce competition in China, and unstable economic policies.

• 한국항해항만학회지
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• 제40권5호
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• pp.311-316
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• 2016

Vietnam is one of Asia's fastest developing economies. A long coastline of nearly 3,500 km provides a comparative advantage for Vietnam in developing a seaport system. Despite accounting for only about 30% of Vietnam's traffic volume, the Northern seaports have rapidly developed over the years. However, the location of the container terminals close to the common hinterland are a cause of fierce competition among container terminals. To outperform rivals and improve competitiveness, it is essential to identify the competitive positions of container terminals. This study analyzes the competitive positioning of container terminals in the northern region of Vietnam between 2005 and 2014 by applying the Boston Consulting Group (BCG) matrix in order to assist terminal operators and policy makers to generate strategic planning as well as to improve priorities for development. Otherwise, the period from 2005-2014 aims to clarify the static and dynamic positioning of container terminals. The results demonstrate that the Hai Phong terminal dominates the market, but the Nam Hai Dinh Vu and Dinh Vu terminals are considered as "star" performers. Quang Ninh, Doan Xa, and Transvina are losing their competitive positions in Northern Vietnam.

• 한국가시화정보학회지
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• 제14권2호
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• pp.12-17
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• 2016

In this work, we investigate the flow velocity controllability of a diffuser-type multiple hydrofoil duct by experimental and numerical flow visualization approaches. The flow velocity controllability is analyzed by changing the angle of the hydrofoil near the outlet, which is the diffuser, while the incoming flow velocity is 0.6 m/s in the experiment. When the diffuser angle is changed from 0 to 7.5 degree, the maximum velocity inside the duct is varied from 1.35 m/s to 1.52 m/s. Also, it is shown from the numerical analysis that the maximum velocity is varied from 1.09 m/s to 1.17 m/s in the same condition. Thus, the aspect of the acceleration in the duct due to the increase of the diffuser angle is similar between the both approaches. Therefore, the multiple hydrofoil duct can be used to control the flow speed inside the duct for continuously extracting power close to a rated capacity.

• 천문학회보
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• 제45권1호
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• pp.39.1-39.1
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• 2020

We examine how the mass assembly of central galaxies depends on their location in the cosmic web. The HORIZON-AGN simulation is analysed at z~2 using the DISPERSE code to extract multi-scale cosmic filaments. We find that the dependency of galaxy properties on large-scale environment is mostly inherited from the (large-scale) environmental dependency of their host halo mass. When adopting a residual analysis that removes the host halo mass effect, we detect a direct and non-negligible influence of cosmic filaments. Proximity to filaments enhances the build-up of stellar mass, a result in agreement with previous studies. However, our multi-scale analysis also reveals that, at the edge of filaments, star formation is suppressed. In addition, we find clues for compaction of the stellar distribution at close proximity to filaments. We suggest that gas transfer from the outside to the inside of the haloes (where galaxies reside) becomes less efficient closer to filaments, due to high angular momentum supply at the vorticity-rich edge of filaments. This quenching mechanism may partly explain the larger fraction of passive galaxies in filaments, as inferred from observations at lower redshifts.

• Journal of Astronomy and Space Sciences
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• 제34권3호
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• pp.199-205
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• 2017

A high resolution spectroscopic observation of the red supergiant star RM_1-390 in the Large Magellanic Cloud was made from a 3.6 m telescope at the European Southern Observatory. Spectral resolving power was R=20,000, with a signal-to-noise ratio S/N > 100. We found the atmospheric parameters of RM_1-390 to be as follows: the effective temperature $T_{eff}=4,250{\pm}50K$, the surface gravity ${\log}\;g=0.16{\pm}0.1$, the microturbulent velocity $v_{micro}=2.5km/s$, the macroturbulence velocity $v_{macro}=9km/s$ and the iron abundance $[Fe/H]=-0.73{\pm}0.11$. The abundances of 18 chemical elements from silicon to thorium in the atmosphere of RM_1-390 were found using the spectrum synthesis method. The relative deficiencies of all elements are close to that of iron. The fit of abundance pattern by the solar system distribution of r- and s-element isotopes shows the importance of the s-process. The plot of relative abundances as a function of second ionization potentials of corresponding chemical elements allows us to find a possibility of convective energy transport in the photosphere of RM_1-390.

• 천문학논총
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• 제30권2호
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• pp.75-78
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• 2015

A growing body of evidence has been supporting the existence of so-called "dark molecular gas" (DMG), which is invisible in the most common tracer of molecular gas, i.e., CO rotational emission. DMG is believed to be the main gas component of the intermediate extinction region from Av~0.05-2, roughly corresponding to the self-shielding threshold of $H_2$ and $^{13}CO$. To quantify DMG relative to $H{\small{I}}$ and CO, we are pursuing three observational techniques; $H{\small{I}}$ self-absorption, OH absorption, and THz $C^+$ emission. In this paper, we focus on preliminary results from a CO and OH absorption survey of DMG candidates. Our analysis shows that the OH excitation temperature is close to that of the Galactic continuum background and that OH is a good DMG tracer co-existing with molecular hydrogen in regions without CO. Through systematic "absorption mapping" by the Square Kilometer Array (SKA) and ALMA, we will have unprecedented, comprehensive knowledge of the ISM components including DMG in terms of their temperature and density, which will impact our understanding of galaxy evolution and star formation profoundly.