• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.125.1-125.1
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• 2011

After a short description of the observatory, this presentation will highlight some of the most recent scientific achievements based on CFHT observations and how they benefit from the current instrumentation and novel observing modes proposed to the CFHT users. We will then move to the mid-term future with the development of new spectroscopic capabilities (visible wide-field FTS or near-IR spectro-polarimetry) and the study of a novel wide-field imager in the visible using Ground-Layer AO to provide unprecedented image quality on a large field of view. As an option for the long-term future, the concept of a next generation 10-m class telescope to replace the current CFHT 3.6-m will be described. An emphasis will be given on how CFHT is slowly morphing into an Asia-Pacific Rim observatory and on the role the Korean community could play in such an endeavor, from immediate access to first-class astronomical data to partnering with other nations in exciting developments.

• 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.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.495-505
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• 2003

Convective weather systems such as organized mesoscale convective systems (Mesoscale Convective Complex, MCC and Convective Cloud Clusters, CCC) and much weaker Disorganized Short-lived Convection (DSC) in the region of India and Nepal were analyzed using the Meteosat-5 IR imagery. The diurnal march and propagation of patterns of convective activity in the Himalayas and Northern Indian subcontinent were examined. Results indicate that infrared satellite images of Northern India and along the southern flank of the Himalayas reveal a strong presence of convective weather systems during the 1999 and 2000 monsoons, especially in the afternoon and during the night. The typical MCCs have life-times of about 11 hours, and areal extent about $300,000km^2$. Although the core of MCC activity remains generally away from the Middle Himalayan range, the occurrence of heavy precipitation events in this region can be directly linked to MCCs that venture into the Lesser Himalayan region and remain within the region bounded by $25^{\circ}-30^{\circ}N$. One principal feature in the spatial organization of convection is the dichotomy between the Tibetan Plateau and the Northern Indian Plains: CCCs and DSCs begin in the Tibetan Plateau in the mid-afternoon into the evening; while they are most active in the mid-night and early morning in the Gangetic Plains and along the southern facing flanks of the Himalayas. Furthermore, these data are consistent with the daily cycle of rainfall documented for a network of 20 hydrometeorological stations in Central Nepal, which show strong nocturnal peaks of intense rainfall consistent with the close presence of Convective Weather Systems (CWSs) in the Gangetic Plains (Barros et al. 2000).

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.59-61
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• 2017

The AKARI 9 and 18 µm diffuse maps reveal the all-sky distribution of the interstellar medium with relatively high spatial resolution of ~6". The zodiacal light is a dominant foreground component in the mid-infrared. Thus, removal of the zodiacal light is a critical issue to study low surface brightness Galactic diffuse emission. We carried out modeling of the zodiacal light based on the Kelsall model which is constructed from the COBE data. In the previous study, only a time-varying component of the zodiacal light brightness was used for determination of the model parameters. However, there remains a residual component of the zodiacal light around the ecliptic plane even after removal with the model. Therefore, instead of using a time-varying component, we use the absolute brightness of the zodiacal light and we find that the new model can better remove the residual component. As a result, the best-fit model parameters are changed from those in the previous study. We discuss the properties of the zodiacal light based on our new result.

• Korean journal of applied entomology
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• v.37 no.2
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• pp.117-121
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• 1998

This experiment was conducted to investigate host preference, occurrence and intraplant distribution of Trialeurodes vaporariorum (Westwood) and Encarsia formosa (Gahan) in greenhouse. T vaporariorum preferred cucumber over tomamto. 7: vaporariorum adults distributed at upper part of cucumber plant. Nymphs also distributed at upper part in early growing stage of cucumber but became to distribute lower part after 40 days. E. formosa adults were found mainly at mid-upper part of plant but there was no significant difference in statistics all analysis among each parts and also mummy distributed mid-low part. E. formosa were released when five ir: vaporariorum were caught by yellow sticky trap per week in glasshouse. The treatment of one tag (50 mummies) of E. formosa per five plants controlled successfully the 7: vaporariorum population after 40 days.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.6
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• pp.272-276
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• 2004

Inorganic materials, including gemstones, also have characteristic vibrational energies in the infrared that can be used for identification. For infrared spectroscopy, absorptions associated with the vibrations of the crystal structure (lattice vibrations) are characteristic of the given combination of atoms constituting the gemstone. Natural turquoise $CuAl_6(PO_4)_4\cdot(OH)_8\cdot 5H_2O$ can be distinguished easily from its common substitutes in the infrared range 2000~450$\textrm{cm}^{-1}$ by features in the mid-infrared. Gilson turquoise, which is a synthetic, exhibits a significantly smoother pattern when compared with natural turquoise, because of a different state of aggregation. Also, because the natural turquoise and gibbsite are so different chemically, their patterns are very different. The technique, which is infrared spectroscopy, is nondestructive and, with Fourier transform instrumentation, extremely rapid.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.577-585
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• 2010

This paper is a part of developing a software that predicts the infrared signal emitted from a ground object by considering solar irradiation. The radiance emitted from a surface can be calculated by using the temperature and optical characteristics of the surface object. The bidirectional reflectance distribution function (BRDF) is defined as the ratio of reflected radiance to incident irradiance. It is a very important surface reflection property that decides the reflected radiance from the object. In this paper, the spectral radiance received by a remote sensor over the mid-wave infrared(MWIR), and the long-wave infrared(LWIR) regions are computed and compared each other for several different materials. The results show that the optical surface properties such as the BRDF and the emissivity of the object surface can play a major role in generating the infrared signatures of various objects, and the largest infrared signal may reach up to 10 times the smallest one when the infrared signals obtained from a flat plate with different surface conditions under the sun light.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.97.1-97.1
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• 2013

적외선 분광 관측은 상대적으로 온도가 낮은 태양계 천체를 연구하는데 있어서 매우 강력한 관측 기술이다. 특히 근적외선 및 중적외선 분광선은 태양계 천체의 지표 및 대기의 성질에 대해서 많은 정보를 주는 파장대이다. 따라서 우주탐사선 뿐만 아니라 지상 망원경으로도 근적외선 및 중적외선 영역의 분광관측은 지속적으로 관측이 수행되고 있는 영역이다. 이렇게 획득된 분광선은 모델링의 과정을 통하여 천체의 구성성분, 생성 과정 및 생성 시기, 물리, 화학적 진화 등을 연구할 수 있다. 본 연구에서 개발 중인 3~5 micron 중적외선 분광기 지상모델은 향후 태양계 천체들에서 물 또는 얼음을 찾을 수 있는 가능성이 있는 파장대이며, 또한 국내에서 개발된 적이 없는 파장대이다. 본 연구에서는 우주탐사선에 탑재된 중적외선 분광기에 의해 관측된 지표를 가진 태양계 천체 (수성, 금성, 화성, 타이탄, 혜성, 소행성)들의 연구 사례를 조사하였다. 이 자료는 본 연구에서 개발하고자 하는 중적외선 분광기 지상모델의 완성 단계에서 지표를 가진 태양계 천체, 특히 달에 대한 과학적 임무를 결정하는데 중요한 역할을 할 것으로 기대하고 있다.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.151-162
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• 1998

Infrared absorption spectra of 9 bulk samples and 3 acid residues of meteorites were obtained in the mid-infrared region ($4000~400cm^{-1}$). From the know composition of meteorites studied, the possible absorption modes were investigated. Most bands of bulk samples occur in the region below $1200cm^{-1}$ and they are due to metallic oxides and silicates. The spectra of each group can be distinguished by its own characteristic bands. Acid residues show very distinct features from their bulk samples, and absorp-tion bands due to organic compounds are not evident in their spectra. Quantiative analyses for two carbonaceous (Allende CV3 and Murchison CM2) and one ordinary (Carraweena L3.9) chondrites were performed for the presence of fullerene ($C_{60}$) in the meteorites. We calculated the concentration of $C_{60}$ in the acid residues by curve-fitting the spectra with Gaussian functions. The upper limit of $C_{60}$ concentration in these meteorites appears to be less than an order of a few hundred ppm.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.53.2-53.2
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• 2014

Radial color gradient of early type galaxies (ETGs) is a key tool for studying the evolution of these galaxies. In this work, we investigated whether ETGs having negative or positive color gradients show any distinguishable characteristics in the galaxy properties. We selected sample of 211 ETGs at 0.01 < z < 0.5 in the Spitzer FLS field, then we constructed u-R color gradients. We obtained the stellar mass, specific star formation rate and fluxes of emission lines of each ETG from MPA-JHU DR7 catalog. Spitzer IRAC and MIPS 24 micron data were used to detect dust emission from the ETGs. Preliminary result shows that less massive galaxies are likely to have positive color gradients, which is probably due to the ongoing star formation in the galaxy core. Almost all AGNs have negative color gradients. This probably is because AGNs are located in relatively massive galaxies with little ongoing star formation. There exists a marginal difference in the percentage of galaxies with PAH emission between ETGs having positive color gradient and negative color gradient. This also supports that ETGs with positive color gradient are galaxies having enhanced star formation.