• Iberoamérica
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• v.13 no.1
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• pp.211-254
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• 2011

O presente trabalho pretende explorar a relação entre a língua nacional e a construção da idenidade nacional no Brasil, materializando os enunciados da "Casa-grande & Senzala" de Gilberto Freyre e os discursos cruzados entre Freyre e romancistas. Atualmente, o português brasileiro é uma manifestação mais extensa e mais profunda da alma multiforme da nacionalidade brasileira como a língua é um tópico essencial no processo de constituição da nacionalidade, ao lado da geografia, da história e da étnia. Junto com o português brasileiro, como o idioma oficial do Brasil, tradições, ideias nacionais se difundiam por todos os habitantes dessa comunidade imaginária. Ao invés dos temas clássicos(como a mestiçagem e a história da vida privada) de Gilberto Freyre, neste trabalho, discutimos as interpretações que Gilberto Freyre fez pelo prisma do luso-tropicalismo sobre a língua e a identidade nacional no Brasil, considerando o cruzamento da Casa-grande e da Senzala representadas na estrutura das obras dos romancistas brasileiros.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.50.1-50.1
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• 2021

Gravitational instability (GI) can produce massive gas giants on wide orbits by fragmentation of protoplanetary disks (PPDs). While most previous works focus on PPDs around solar mass stars, gas giants have been observed in systems with a wide range of stellar masses including M dwarfs. We use the GIZMO code to perform global three-dimensional simulations of self-gravitating disks around low-mass stars. Our models consider heating by turbulent viscosity and stellar irradiation and the β cooling occurring over the dynamical time. We run various models with differing disk-to-star mass ratio q and disk temperature. We find that strongly gravitating disks either produce spirals or undergo fragmentation. The minimum q value for fragmentation is 0.2-0.7, with a smaller value corresponding to a more massive star and/or a smaller disk. The critical q value depends somewhat sensitively on the disk temperature, suggesting that the stellar irradiation is an important factor in determining GI. We discuss our results in comparison with previous work as well as recent ALMA observations.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.35.1-35.1
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• 2021

Variability in young stellar objects (YSOs) can be caused by various time-dependent phenomena associated with star formation, including accretion rates, geometric changes in the circumstellar disks, stochastic hydromagnetic interactions between stellar surfaces and inner disk edges, reconnections within the stellar magnetosphere, and hot/cold spots on stellar surfaces. Among these YSO variability phenomena, bursts of accretion, which are the most remarkable variability, usually occur sporadically, making it challenging to catch the bursting moments observationally. However, the burst accretion process significantly affects the chemical conditions of the disk and envelope of a YSO, which can be used as a prominent tracer of episodic accretion. I will introduce our ensemble studies of YSO variability at mid-IR and submillimeter and also cover the ALMA observations of several YSOs in the burst accretion phase, especially in the view of chemistry.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.261-262
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• 2012

The aim of this research is to reveal the spatial distribution of the star formation activity of nearby galaxies by comparing CO molecular emission lines with the large area observation in far-infrared (FIR) lines. We report the imaging observations of NGC 253 by FIR forbidden lines via FIS-FTS and CO molecular lines from low to high excitation levels with ASTE, which are good tracers of star forming regions or photo-dissociation regions, especially spiral galaxies, in order to derive the information of the physical conditions of the ambient interstellar radiation fields. The combination of spatially resolved FIR and sub-mm data leads to the star formation efficiency within galaxy. The ratio between the FIR luminosity and molecular gas mass, $L_{FIR}/M_{H_2}$, is expected to be proportional to the number of stars formed in the galaxy per unit molecular gas mass and time. Moreover the FIR line ux shows current star formation activity directly. Furthermore these can be systematic and statistical data for star formation history and evolution of spiral galaxies.

• Food Science of Animal Resources
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• v.40 no.1
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• pp.96-105
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• 2020

The appearance of white striations over breast meat is an emerging and growing problem. The main purpose of this study was to employ the reflectance of visible-near infrared (VIS/NIR) spectroscopy to differentiate between normal and white striped turkey breasts. Accordingly, 34 turkey breast fillets were selected representing a different level of white striping (WS) defects (normal, moderate and severe). The findings of VIS/NIR were analyzed by principal component (PC1) analysis (PCA). It was found that the first PC1 for VIS, NIR and VIS/NIR region explained 98%, 97%, and 96% of the total variation, respectively. PCA showed high performance to differentiate normal meat from abnormal meat (moderate and severe WS). In conclusion, the results of this research showed that VIS/NIR spectroscopy was satisfactory to differentiate normal from severe WS turkey fillets by using several quality traits.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1529-1532
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• 2001

ACE 2000 ATM 교환기를 이용하여 MPLS 교환기를 구현 시, ATM 가입자 및 중계선을 수용하여 스위치와 정합 기능을 수행하는 AIM(ATM interface module)에 IP 패킷에 대한 룩업을 수행하여 ATM 스위치로 패킷을 포워딩하는 HFEA(High performance Forwarding Engine board Assembly)를 연동하기 위해서는 UTOPIA Level2 연결이 요구된다. 그러나 HFEA 에서 622Mbps 급 성능의 MXT4400(SAR) 칩은 TSAR(Transmit SAR)로 운용 시 Master모드로 동작하게 되고, AIM 모듈 또한 Rx에서 Master모드로 동작하기 때문에 이들을 연결하기 위해서는 양 모듈간에서 Slave 모드로 동작할 수 있는 UTOPIA Controller가 필요하게 된다. 이에 따라 ALMA(AW Layer Module Assembly)칩과 HFEA TSAR 사이에서 데이터를 전달하는 UTOPIA Controller를 Xilinx를 이용해 FPGA로 구현하였다.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.66.2-66.2
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• 2016

KASI and NAOJ are making collaborating efforts to implement faster mapping capability into the new 275-500 GHz Atacama Submillimeter Telescope Experiment focal plane array (FPA). Feed horn antenna is one of critical parts of the FPA. Required fractional bandwidth is almost 60 % while that of traditional conical horn is less than 50 %. Therefore, to achieve this wideband performance, we adopted a horn of which the corrugation depths have a longitudinal profile. A profiled horn has features not only of wide bandwidth but also of shorter length compared to a linear-tapered corrugated horn, and lower cost fabrication with less error can be feasible. In our design process the flare region is represented by a cubic splined curve with several parameters. Parameters of the flare region and each dimension of the throat region are optimized by a differential evolution algorithm to keep >20 dB return loss and >30 dB maximum cross-polarization level over the operation bandwidth. To evaluate RF performance of the horn generated by the optimizer, we used a commercial mode matching software, WASP-NET. Also, Gaussian beam (GB) masks to far fields were applied to give better GB behavior over frequencies. The optimized design shows >23 dB return loss and >33 dB maximum cross-polarization level over the whole band. Gaussicity of the horn is over 96.6 %. The length of the horn is 12.5 mm which is just 57 % of the ALMA band 8 feed horn (21.96 mm).

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.93-97
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• 2015

How high-mass stars form is currently unclear. Calculations suggest that the radiation pressure of a forming star can halt spherical infall, preventing further growth when it reaches $10M_{\odot}$. Two major theoretical models on the further growth of stellar mass have been proposed. One model suggests the merging of less massive stellar objects, and the other is through accretion, but with the help of a disk. Inflow motions are key evidence for how forming stars gain further mass to build up massive stars. Recent developments in technology have boosted the search for inflow motion. A number of high-mass collapse candidates were obtained with single dish observations, and mostly showed blue profiles. Infalling signatures seem to be more common in regions which have developed radiation pressure than in younger cores, which is the opposite of the theoretical prediction and is also very different from observations of low mass star formation. Interferometer studies so far confirm this tendency with more obvious blue profiles or inverse P Cygni profiles. Results seem to favor the accretion model. However, the evolution of the infall motion in massive star forming cores needs to be further explored. Direct evidence for monolithic or competitive collapse processes is still lacking. ALMA will enable us to probe more detail of the gravitional processes.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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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.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.59.1-59.1
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• 2019

Immediate vicinity of a supermassive black hole (SMBH) is an important place to test general relativity in strong gravity regime. Also, this is a place where mass accretion and jet formation actively occurs at the centers of active galaxies. Theoretical studies predict presence of bright ring-like emission encircling an accreting SMBH with a diameter of about 5 Schwarzschild radii, and a flux depression at the center (i.e., BH shadow). Direct imaging of the BH shadow is accordingly of great importance in modern astrophysics. However, the angular sizes of the horizon-scale structures are desperately small (e.g., ~40-50 microarcseconds (uas) diameter for the nearest best candidates). This poses serious challenges to observe them directly. Event Horizon Telescope (EHT) is a global network of sensitive radio telescopes operating at 230 GHz (1.3 mm), providing ultra-high angular resolution of 20 uas by cutting-edge very long baseline interferometry techniques. With this resolution, EHT aims to directly image the nearest SMBHs; M87 and the galactic center Sgr $A{\ast}$ (~40-50 uas diameters). In Spring 2017, the EHT collaboration conducted a global campaign of EHT and multiwavelength observations of M87 and Sgr $A{\ast}$, with addition of the phased ALMA to the 1.3mm VLBI array. In this talk, I review results from past mm-VLBI and EHT observations, provide updates on the results from the 2017 campaign, and future perspectives.