• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.32.2-32.2
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• 2016

The globular cluster (GC) systems in most elliptical galaxies show bimodal color distributions. This phenomenon has been generally regarded as a bimodal metallicity distribution, indicating the presence of two sub-populations in a GC system. However, since a new explanation on the bimodality was introduced where the nonlinear metallicity-to-color conversion can cause bimodal color distributions, the origin of this phenomenon has been under hot debate. In this presentation, we briefly review the ten-year debate on the origin of GC color bimodality, and present our recent pieces of evidence on the nonlinear nature of GC color-metallicity relations.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.66.4-67
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• 2016

Our recent investigation (Lee et al. 2015) suggests that the presence of double red clump in the Milky Way bulge is another manifestation of multiple populations observed in halo globular clusters. The origin of Helium enhancement in the 2nd generation population (G2), however, is not yet fully understood. Here we investigate the origin of this super-Helium-rich population in the framework of self-enrichment scenario. We find that chemical enrichments and pollutions by asymptotic giant branch stars and winds of massive rotating stars can naturally reproduce the observed Helium enhancement. The Helium to metal enrichment ratio appears to be ${\Delta}Y/{\Delta}Z=6$ for G2, while the standard ratio, ${\Delta}Y/{\Delta}Z=2$, is appropriate for G1, which is probably enriched mostly by typeII supernovae.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.71.1-71.1
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• 2016

Photometric reverberation mapping is an effective alternative to time consuming spectroscopy. It usually employs narrow bands to track the luminosity variations of broad emission lines, such as Balmer lines, and broadbands for the continuum variability. Here, we investigate the feasibility of substituting these for medium bands, with 50nm widths, that are currently being used on the SED Camera for QUasars in EArly uNiverse (SQUEAN) installed on the 2.1m Otto Struve Telescope at McDonald Observatory. Three targets with recent variability and/or short expected time lags were selected, and observed for 15 minutes each in the medium band containing $H{\alpha}$, and the two adjacent bands for continuum subtraction afterwards. Analysis shows that for one of the objects, SDSS J0350+0037, the pure $H{\alpha}$ emission line flux has a S/N ~ 12, so that variabilities up to ~ 8% are detectable. Thus, future observations using these medium bands on SQUEAN seem to be practical.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.5
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• pp.694-698
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• 2000

In the cylindrical coordinate, the origin r = 0 plays a role of the singularity and thus much care is needed to treat near-origin region. This work presents a new numerical scheme which is derived from the exact solution under the one-dimensional assumption in the radial direction. It is shown that the near-origin region can be properly treated by the radial-exponential scheme, whereas the numerical results from the conventional exponential scheme deviate considerably from the exact solution. Over the region of small ($ {\delta}r_e/r_e$ the present radial-exponential scheme turns out to be almost the same as the exponential scheme.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.4
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• pp.203-207
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• 2015

Osteomyelitis is classified into three groups according to its origin: osteomyelitis that originates from the blood supply, osteomyelitis related to bone disease or vascular disease, and osteomyelitis related to a local infection of dental or non-dental origin. The present case involved osteomyelitis related to a local infection of dental origin and was located in the rear area of the lingula of the mandible. We decided to use sagittal split ramus osteotomy to access the osteomyelitis area. Under general anesthesia, we successfully performed surgical sequestrectomy and curettage via sagittal split ramus osteotomy.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.367-369
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• 2015

The FastSound project is a galaxy redshift survey using Subaru/FMOS to detect $H{\alpha}$ emitting galaxies at z ~ 1:3, for the purpose of probing the origin of the accelerated expansion of the universe. The survey has detected ~4,000 galaxy redshifts in a total area of $30deg^2$, and detected the redshift space distortion at this redshift range for the first time. The redshift space distortion (RSD) signal will be used to derive a measurement of the growth rate of large scale structure, which will provide a test for modified gravity as a possible origin of accelerated cosmic explansion. Here we present an overview and the current status of the project.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.475-476
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• 2015

We analyze the host galaxy of the tidal disruption object, Swift J1644+57, based on long-term optical to NIR data obtained with CQUEAN and UKIRT WFCAM observations. We decompose the bulge component using high resolution HST WFC3 images. We conclude that the host galaxy is bulge dominant. We investigate optical to NIR light curves and estimate the multi-band fluxes of the host galaxy. We fit spectral energy distribution (SED) models in order to determine the stellar mass. Finally, we estimate the mass of the black hole in the center of the host galaxy based on several scale relations.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.72.1-72.1
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• 2012

Sheen et al. 2012 reported a high fraction of galaxies with post-merger features in clusters. The fraction is much higher than what analytic calculation predicts based on the fact that subhalos inside galaxy clusters have high relative velocities. In this study, we aim to address the origin of the post-merger features and to draw an implication for the assembly history of the cluster galaxies. We have performed high-resolution hydrodynamic zoom-in simulations on a cluster of ~1015M using the publicly available Adaptive Mesh Refinements (AMR) code, RAMSES. From the simulations, we have constructed mock images of cluster galaxies taking into account age, metallicity, mass of stellar populations and extinction. The mock images enable us to directly compare the simulation result with deep observation data of cluster galaxies. We discuss possible scenarios for the origin of the post-merger features. We also discuss caveats and future perspectives from the study.

• Food Science and Industry
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• v.53 no.2
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• pp.134-147
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• 2020

Northeast Asia comprises many characteristic cultural areas including China, Mongolia, Korea and Japan. These areas have their own traditional food cultures, and Korea is known as the home of fermented foods in this region. The origin of Northeast Asian fermented foods, cereal alcoholic beverages, fermented vegetables(kimchi), fermented fish and fermented soybean products were investigated in relation to the primitive earthen vessels developed in this region. The geographical and environmental background of the appearance of primitive pottery culture in the Korea Strait region, and its influence on the development of fermentation technology in Northeast Asia were reviewed focusing on Korean dietary culture.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.38-46
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• 2016

Purpose: study for discriminating method of origin side vibration from non-symptomatic clicking group. Materials and Methods: 60 joints vibrations of 30 subjects in non-symptomatic clicking group was recorded via subject's awareness, examiner's palpation and JVA analysis. Origin side vibration was discriminated with consideration for frequency spectrum, time delay and phase shift of waveforms, analysis of numeric values. Results: There were all unilateral vibrations with JVA analysis and number of origin vibrations were 42. 11 pairs of vibrations showed time delay and phase shift and transferred side vibrations showed smaller values of total integral and bigger values of > 300 / < 300 ratio than origin side vibrations except one pair of vibrations. Also as the ipsi-lateral joint vibrations with smaller values of total integral showed bigger values of > 300 / < 300 ratio than the contra-lateral joint vibrations and there all ipsi-lateral vibrations were showed small values of total integral below 10 and hard to detect time delay and phase shift. So the features were used in discrimination of origin side vibrations. Conclusion: There should be all-around considerations for discrimination of origin side vibrations that is frequency spectrum, phase shift and time delay and analysis of numeric values.