• Publications of The Korean Astronomical Society
• /
• v.32 no.1
• /
• pp.309-311
• /
• 2017

Properties of ULIRGs (Ultra Luminous InfraRed Galaxies) are important to understand the cosmic star formation history. To investigate their properties up to z=0.3, we search for ULIRGs identified by using the AKARI/FIS Bright Source Catalogue and the WISE All-Sky catalog. By matching the AKARI $90{\mu}m$ catalogue with the WISE catalog, we selected 3,452 galaxies. Additionally, combined with the SDSS DR10 spectroscopic data, we selected 952 galaxies with spec-z. We then computed total infrared luminosities using SED fitting technique, and identified 31 ULIRGs, 561 LIRGs and 344 IRGs. For these galaxies, we found an indication that ULIRGs selected by AKARI change the SED shape with redshift (z = 0.1 - 0.3).

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.2
• /
• pp.29.5-30
• /
• 2016

(1) The correlation between the mass of supermassive black holes (SMBHs) and the properties of their host galaxies suggests that SMBHs and host galaxies are closely linked in their formation and evolution. While the exact origin of their relationship is still under debate, theoretical models often invoke feedback from active galactic nuclei as a crucial mechanism for establishing the BH-host correlation. In the first part of my talk, I will present our efforts to find observational sign of the AGN feedback in young luminous AGNs. (2) While intermediate-mass black hole (IMBH) is thought be cosmologically important class to understand the link between stellar mass black holes and SMBHs, it is extremely rare in the present-day Universe. In the second part of this talk, I will report a Gemini/GMOS-N IFU study of an ultraluminous X-ray source in NGC 5252, which is a possible candidate of an off-nuclear non-stellar black hole.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1189-1192
• /
• 2008

A new mercury-free flat fluorescent lamp with a single cell having dimension 2.2inches across the diagonal, had been developed which shows a wide, stable operating voltage margin, high luminance and luminous efficacy by adopting the bipolar pulse drive scheme. In this paper, the single cell is expanded into a multi-structured configuration to realize a 32inch sized panel across the diagonal by a simple repetition of the single cells. A driving scheme is proposed for a 2-bit areal selective dimming using dual auxiliary electrodes and bipolar drive scheme.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.1
• /
• pp.27.4-27.4
• /
• 2017

(1) The correlation between the mass of supermassive black holes (SMBHs) and the properties of their host galaxies suggests that SMBHs and host galaxies are closely linked in their formation and evolution. While the exact origin of their relationship is still under debate, theoretical models often invoke feedback from active galactic nuclei as a crucial mechanism for establishing the BH-host correlation. In the first part of my talk, I will present possible observational biases in the BH-host relation, and methods to overcome these biases. I will also report our efforts to find observational sign of the AGN feedback in high-z young luminous AGNs. (2) While intermediate-mass black hole (IMBH) is thought be cosmologically important class to understand the link between stellar mass black holes and SMBHs, it is extremely rare in the present-day Universe. In the second part of this talk, I will report a Gemini/GMOS-N IFU study of an ultraluminous X-ray source in NGC 5252, which is a possible candidate of an off-nuclear non-stellar black hole.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.1015-1019
• /
• 2002

The deposition of $SrGa_2S_4$ thin film phosphors doped with Ce or Eu aiming at application for FEDs has been carried out by a multi-source deposition technique. A $SrGa_2S_4$ phase was formed by annealing process and $SrGa_2S_4$ thin films which were deposited using a $Ga_2S_3/Sr$ flux ratio larger than 50 and annealed in $H_2$S showed luminance and luminous efficiency of about 1700 cd/$m^2$ and 2.95 lm/W, respectively, with (0.13, 0.10) chromaticity in the activation with Ce, and about 4000 cd/$m^2$ and 7.05 lm/W, respectively, with (0.36, 0.60) under excitation with 3 kV and 60A/$cm^2$. The results obtained this experiment demonstrate the potential of $SrGa_2S_4$ thin film phosphors for FED screens.

• Journal of Conservation Science
• /
• v.36 no.4
• /
• pp.236-243
• /
• 2020

In this study, an accelerated aging experiment for fabric and paper was conducted using two light emitting diode(LED) sources with different wavelength characteristics, and the discoloration under each lighting type was examined. Hanji(Korean traditional paper) and related textiles showed more discoloration under blue LEDs, while the blue wool standard showed more discoloration under white LEDs. This, indicated that the deterioration varied depending on the sample color. The the effect of the light source on artifact deterioration was primarily related to the total radiation flux(expressed in mill watts), rather than the total luminous flux(expressed in lumens). In addition, the discoloration of the investigated artifacts was dependent on the color rendering of the lighting.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2196-2198
• /
• 2005

The luminous intensity distribution of a 1W high-power LED with a wide view angle should be concentrated to be used as a light source for an automotive reading lamp. In this paper, an optical lens made of PMMA is simulated by using an optical design software for that purpose. As the result, with the help of the devised lens, the reading light gives over 80 lx at the center of a target surface of radius of 0.2m located below 0.5m from the lamp, and a minimum of 20 lx at the perimeter of the target surface. Thus, a 1W high-power LED with an appropriate lens would suffice for an automotive reading lamp.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.1
• /
• pp.24-32
• /
• 2008

The ultimate purpose of the study is to develop a discomfort glare forecasting formula that can be practically used in Korea in order to effectively forecast discomfort glare considering the optical characteristics of the Koreans. The study was to examine the relations between discomfort glare and the variables such as luminance, background luminance, solid angle, luminous area and louver. To this end, experiments were conducted in a mock-up office that emulates the lighting environment of an ordinary office. The study was conducted by four steps as follow. First, previous studies on discomfort glare rating to define and rate discomfort glare were analyzed and modified to be applied to the experiments of this study. Second, experiment variables, variable scope, evaluation objects and evaluation points were determined after review on existing discomfort glare evaluation experimental formulas. Third, experiments were conducted in a mock-up office to be able to control variables. Finally, sensitivity of experiment variables were analyzed through examination of the relation between discomfort glare and the variables such as luminance, solid angle, louver, luminous area and subject's position. The result showed that the most influential variables on discomfort glare of an artificial light source is luminance and louver, luminous area and subject's position(solid angle) followed.

• Korean Journal of Optics and Photonics
• /
• v.26 no.2
• /
• pp.73-82
• /
• 2015

This work demonstrates the indoor SI-traceable calibration of a transmissometer with a 75-m baseline for the measurement of visibility in MOR (Meteorological Optical Range). The calibration is performed using a set of neutral density (ND) filters (OD 0.1-2.5) and a set of high-transmission quartz glass plates (a bare quartz glass plate and antireflective-coated quartz glass plates), the collection consisting of 20 artifacts in total. The luminous transmittance values of the reference artifacts had been calibrated traceable to the KRISS spectral transmittance scale, which ranges from 0.2 % to 99.5 %. The transmissometer to be calibrated typically consists of a loosely collimated light source based on a white LED (CCT ~5000 K) and a luminous intensity detector with a CIE 1924 V(${\lambda}$) spectral response. As a result of calibration, we obtained the MOR error and its uncertainty for the transmissometer in 20 m - 40 km of MOR. Based on the results, we investigated the applicability of the calibration method and the conformity of the transmissometer to the ICAO's (International Civil Aviation Organization) accuracy requirement for meteorological visibility measurement. We expect that this work will establish the standard procedure for the SI-traceable calibration of a transmissometer.

• Korean Chemical Engineering Research
• /
• v.49 no.3
• /
• pp.320-324
• /
• 2011

TOPO/TOP capped CdSe nanoparticles were synthesized via thermal-solvent method. The 540 nm green and 620 nm red emitting CdSe nanoparticles were obtained by controlling the reaction time and temperature. Phosphor conversion white LED was produced combining a 460 nm emitting InGaN LED chip as an excitation source with 540 and 620 nm CdSe nanoparticles as phosphors. The single or double phosphor layer was fabricated by mixing with epoxy, and investigated the effects on the luminous properties of the white LED. The single phosphor layer white LED showed 5.78 lm/W with CIE of (0.36, 0.45) in reddish white, and the double phosphor layer white LED showed 7.28 lm/W with that of (0.32, 0.34) in pure white at 20 mA. When the 400 nm near-UV LED was applied to optical pumping source, the luminous efficiency of white LED was enhanced to 8.76 lm/W.