• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.68.3-69
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• 2021

We present a novel profile stacking technique based on optimal profile decomposition of a 3D spectral line data cube, and its performance test using the HI data cubes of sample galaxies from HI galaxy surveys, THINGS and LITTLE THINGS. Compared to the previous approach which aligns all the spectra of a cube using their central velocities derived from either moment analysis, single Gaussian or hermite h3 polynomial fitting, the new method makes a profile decomposition of the profiles from which an optimal number of single Gaussian components is derived for each profile. The so-called superprofile which is derived by co-adding all the aligned profiles from which the other Gaussian models are subtracted is found to have weaker wings compared to the ones constructed in a typical manner. This could be due to the reduced number of asymmetric profiles in the new method. A practical test made on the HI data cubes of the THINGS and LITTLE THINGS galaxies shows that our new method can extract more mass of kinematically cold HI components in the galaxies than the previous results. Additionally, we fit a double Gaussian model to the superprofiles whose S/N is boosted, and quantify not only their profile shapes but derive the ratio of the Gaussian model parameters, such as the intensity ratio and velocity dispersion ratio of the narrower and broader Gaussian components. We discuss how the superprofile properties of the sample galaxies are correlated with their other physical properties, including star formation rate, stellar mass, metallicity, and gas mass.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.71.2-71.2
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• 2021

Using multi-epoch spectra of active galactic nuclei (AGN) obtained from the Sloan Digital Sky Survey, we identify 16 spectrally variable sources, for which the spectral shapes of broad emission lines significantly vary with a time scale of yrs. Out of them, 3 AGNs are already known as changing-look (CL) AGNs by previous studies. 6 AGNs are newly identified as CL AGNs from our study. A majority of these AGNs are relatively faint and their variability in the continuum is small, which may explain their non-detection in the previous studies. 7 sources are known as binary AGN candidates based on the systematic velocity offset between broad emission lines and narrow emission lines. For those sources and 3 CL AGNs, we find that the peak of broad emission lines had been shifted up to a few thousands km/s for ~10 years, implying that those can be promising candidates for pc-scale binary AGNs or recoiling black holes. We plan to conduct multiwavelength follow-up studies to nail down the physical origin of the velocity shift.

• Journal of the Korean Society of Clothing and Textiles
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• v.24 no.4
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• pp.605-615
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• 2000

This study was carried out to investigate sound characteristics including sound parameters and subjective sensation, and primary hand values related with sound of fabrics for blouse, and furthermore to predict subjective sound sensation with mechanical properties and sound parameters. Sound of specimens was analyzed by FFT. Level pressure of total sound(LPT), loudness(Z), coefficients of autoregressive(AR) functions for fitting the spectra, and sound color factors(ΔL and Δf) were obtained as sound parameters. Primary hand values for women's thin dress were calculated by using KES-FB. Subjective sensation for sound including softness, loudness, sharpness, clearness, roughness, highness, and pleasantness was evaluated by free modulus magnitude estimation. The results were as follows; 1. Fabrics for blouse showed similar spectral shapes to one another in that amplitude values were lower in most ranges of frequencies than fabrics for other uses. 2. It was found that fabrics for blouse were less louder because LPT, loudness(Z), and ARC values were lower than other fabrics. 3. Primary hand values indicated that specimens were soft-touched, flexible, and less crisp. Among primary hands related with sound, Shari values were higher for silk fabrics than for synthetic ones, while the values for Kishimi were similar, 4. Fabrics for blouse were rated more highly for softness, clearness, and pleasantness than for loudness, sharpness. roughness, and highness. Silk fabrics were evaluated more pleasant than synthetic fabrics. 5. Subjective sensation for sound of blouse fabrics were predicted with mechanical properties and physical sound parameters.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.541-554
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• 2010

Fifteen min-microtremor data sets were collected at 136 sites from a coastal area of Kunsan and 117 sites from an inland area of Jeonju located in SW Korea, and were analyzed for the HVSR (Horizontal to Vertical Spectral Ratio) of the sites. The microtremor spectra of the coastal area have stronger energy in the lower frequency range from 1-6 Hz than those of the coastal area. This result can be attributed to the effect of the waves and tides in the Keum river and the Yellow sea. Twenty four hours of measurement of the microtremor indicated that the microtremor spectrum correlates with the human activities, but the microtremor HVSR peak was observed consistently at the characteristic frequency for the site. The HVSR peaks were grouped into 4 types -"single peak", "double peak", "broad peak" or "no peak"- based on their shapes. More than 90% of the data sets exhibit peak frequencies ($F_0$) which can be easily identified. The distribution of $F_0$ reveals a close relationship with the topography and local geology of the areas, exhibiting high F0s in the hillside areas and low $F_0s$ in the reclaimed land area. While the amplitudes of microtremor HVSR peak frequencies are less than 4 in the downstream of the inland area, those of the recently reclaimed land in the coastal area are extremely high (more than 10). The results of this study indicate that detailed HVSR studies are essential for the earthquake hazard reduction of reclaimed lands.

• Economic and Environmental Geology
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• v.19 no.spc
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• pp.207-226
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• 1986

The skarn type tungsten deposits in Jechon area are developed in the contact aureole of Jurassic granodiorite and lower Paleozoic limestone beds. The Tong Myeong mine contains scheelitebearing skarns found at and near the contacts between crystalline limestone and hornfels. Although the skarns are heterogeneous, there are clear patterns in the preferred associations and nonassociations of minerals on all scales. The skarn show a zonal arrangement from limestone to hydrothermal vein as follow: wollastonite skarn, clinopyroxene skarn, clinopyroxene-garnet skarn, garnet skarn, and vesuvianite skarn. Scheelite, abundant in all skarn units except wollastonite skarn and also in quartz veins near orebodies, is everywhere strongly correlated with pyrrhotite. It is implied that it was a stable phase throughout the evolution of the zoned skarns, at least in pyrrhotite.forming environments. Deposition of scheelite was probably widely caused by increasing $a_{Ca^{2+}}$ in the fluid, resulting from associated and interrelated reactions: $FeCl_2\;aq+H_2S\;aq{\rightarrow}FeS+2H^{+}+2Cl^-$; and $CaCO_3+2H^+{\rightarrow}Ca^{+2}+H_2CO_3$. The spectral reflection powers of nine sulfide species were studied, for three mineralization stage. The shapes and characteristics of the spectral reflectivity profiles are significant in their control of other optical properties. The characteristics of the Vickers microhardness and the optical symmetry for the minerals studied are discussed. Broad radicle groupings of the sulfides can be made with regard to the reflectivity-microhardness values.