• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.401-403
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• 2015

We present the results of the analysis of FLS 1718+59, a galaxy-galaxy gravitational lens system in the Spitzer First Look Survey (FLS) field. A background galaxy ($z_s=0.245$) is severely distorted by a nearby elliptical galaxy ($z_l=0.08$), via gravitational lensing. The system is analysed by several methods, including surface brightness fitting, gravitational lens modeling, and spectral energy distribution fitting. From Galfit and Ellipse we measure basic parameters of the galaxy, such as the effective radius and the average surface brightness within it. gravlens yields the total mass inside the Einstein radius ($R_{Ein}$), and MAGPHYS gives us an estimate of the stellar mass inside $R_{Ein}$. By comparing these parameters, we confirm that the lens galaxy is an elliptical galaxy on the Fundamental Plane and calculate the stellar mass fraction inside $R_{Ein}$, and discuss the results with regards to the initial mass function.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.61.3-61.3
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• 2018

To understand the assembly of the galaxy population in clusters today, it is important to first understand the impact of previous environments prior to cluster infall, namely preprocessing. We use 15 cluster samples from hydrodynamic zoom-in simulation YZiCS to determine the significance of preprocessing focusing primarily on the tidal mass loss of dark matter halos. We find ~48% of the cluster member halos were once satellites of another host. The preprocessed fraction is not a clear function of cluster mass. Instead, we find it is related to each individual cluster's recent mass growth history. We find that the total mass loss is a clear function of time spent in a host. However, two factors can considerably increase the mass loss rate. First, if the satellite mass is approaching the mass of its host. Second, when the halo suffers tidal mass loss at a higher redshift. The preprocessing provides an opportunity for halos to experience tidal mass loss for a more extended period of time than would be possible if they simply fell directly into the cluster, and at earlier epochs when hosts were more destructive to their satellites.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.31.2-31.2
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• 2020

Mass segregation, a tendency of more massive galaxies being distributed closer to the cluster center, is naturally expected from dynamical friction, but its presence is still controversial. Using deep optical observations of 14 Abell clusters (KYDISC) and a set of hydrodynamic simulations (YZiCS), we find in some cases a hint of mass segregation inside the virial radius. Segregation is visible more clearly when the massive galaxy fraction is used instead of mean stellar mass. The trend is more significant in the simulations than in the observations. To find out the mechanisms working on mass segregation, we look into the evolution of individual clusters simulated. We find that the degree of mass segregation is different for different clusters: the trend is visible only for low-mass clusters. We compare the masses of galaxies and their dark haloes at the time of infall and at the present epoch to quantify the amount of tidal stripping. We then conclude that satellites that get accreted at earlier epochs, or galaxies in more massive clusters go through more tidal stripping. These effects in combination result in a correlation between the host halo mass and the degree of stellar mass segregation. This is a work submitted to The Astrophysical Journal (under review).

• Fire Science and Engineering
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• v.24 no.5
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• pp.128-135
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• 2010

In this study, a mixture fraction analysis was performed to investigate the characteristics of chemical species production in compartment fires burning hydrocarbon fuels such as methane, heptane, and toluene. A series of fire experiments was conducted in the ISO 9705 standard room, and gas species concentration and soot fraction were measured at two locations in the upper layer of the compartment. The mass fractions of measured chemical species, such as unburned hydrocarbons (UHC), carbon monoxide (CO), carbon dioxide ($CO_2$), oxygen ($O_2$), and soot were presented as a function of mixture fraction and compared with state relationships based on the idealized reaction of hydrocarbon fuels. The mixture fraction analysis made it possible to rearrange hundreds of species measurements, which were done under various fire conditions and at two locations of the upper layer, in term of the unified parameter, i.e. the mixture fraction. The results also showed that inclusion of soot in the mixture fraction calculation could improve the performance of analysis, especially for the sooty fuels such as heptane and toluene.

• Macromolecular Research
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• v.9 no.4
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• pp.228-237
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• 2001

The evolution of conformational constraints in bisphenol-A polycarbonate (BAPC) upon quiescent bulk crystallization was quantitatively analyzed from calorimetric study employing a rigid amorphous fraction (RAF) as an indicator of the level of conformational constraints. From the correlation between corrected crystallinity (X$\sub$c/) and total rigid fraction (f$\sub$r/), it was found that, regardless of molar mass distribution and thermal treatment conditions, semicrystalline BAPC always exhibits greater f$\sub$r/ than X$\sub$c/ maintaining a quantitative relationship of f$\sub$r/〓2X$\sub$c/ in the range of 0.0 $\sub$c/< 0.4. This directly indicates the evolution of approximately the same amount of RAF as X$\sub$c/, (i.e., RAF〓X$\sub$c/) upon bulk crystallization of BAPC. It was also found that T$\sub$g/ per se and T$\sub$g/ broadening enhance as RAF increases, and there appears to be a critical level of RAF (>0.2) needed to initiate significant changes in both quantities.

• Microbiology and Biotechnology Letters
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• v.27 no.3
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• pp.179-183
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• 1999

The volatile components (essential oil) showing antimicrobial activity were extracted from the fruit peel of Zanthoxylum piperitum DC by distillation and separated by thin layer chromatography (TLC). The crude volatile components exhibited antimicrobial activity only at very high concentration. The active fraction obtained by TLC inhibited noticeably the growth of bacteria. The minimum inhibitory concentration (MIC) of the fraction were 150ppm, 300ppm, and 300ppm against Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis, respectively. The components in the active fraction were identified by gas chromatography/mass spectrometry to be geranlyl acetate (60.23%), citronellal(36.01%), citronellol(3.77%), geraniol(0.46%), and cumin ldehyde(0.43%).

• Journal of Applied Biological Chemistry
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• v.44 no.2
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• pp.77-83
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• 2001

For defining the possibilities of the commercial mass liquid culture of Cordyceps sinensis, the pharmacological activities of mycelia were analyzed. The mycelium of C. sinensis consists of carbohydrate (5.1%) and fat (1.3%), and contains a low content of protein (0.7%) and ash (0.5%), and 92.4% moisture. The molecular sugar ratio of carbohydrate was composed mainly of glucose, mannose (1.0 : 0.9), in addition a small amount of galactose and arabinose (0.2 : 0.1). The cellular materials of mycelia were fractionated into ethylacetate (EA), MeOH (M) and hot-water extract fraction (HW). HW fraction showed the most potent intestinal immune system modulating activity, anti-coagulant activity, and anti-complementary activity, and M fraction had the inhibition activity of radical generation as effective as genistine. These results reveal that the mycelium of liquid cultured C. sinensis showed pharmacological activities and could be used for commercial purpose.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.2
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• pp.113-120
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• 2000

Effects of sea-salts on the properties of aerosol collected in a coastal region were studied by applying a gas-particle equilibrium model SCAPE to the measurement data from Korea Cheju Island in summer 1994. It was found that the observed higher ammonium concentrations in fine particles (PM2.5) than in TSP were caused by forced evaporation of ammonium in coarse fraction of aerosol by sea-salts and the degree of evaporation was quantified through an application of SCAPE. By subtracting the sea-salt fraction from the measured concentra-tions the changes of aerosol property were also studied. The concentrations of nitrate at both TSP and PM2.5 decreased when alkaline sea-salt fraction was removed from the measured data. Estimates of aerosol acidity increased for most samples with sea salt loadings, However in some cases with high mass fractions of sea-salt components the aerosol acidity of PM2.5 decreased slightly. This is though to be related with the formation of solid salt with the removal of sea-salts.

• Applied Biological Chemistry
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• v.34 no.4
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• pp.344-352
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• 1991

The whole volatile flavor concentrate obtained from Jindalrae flower was separated into hydrocarbon and oxygen-containing compound(OCC) fractions, and the OCC-fraction was further separated by column chromatography into nine sub-fractions, respectively. These fractions were analyzed by gas chromatography and combined gas chromatography/mass spectroscopy. One hundred and sixty-two components, including 61 hydrocarbons, 18 aldehydes, 18 esters, 41 alcohols, 3 ketones, 4 oxides, 8 acids, 6 phenols and 3 miscellaneous components, were identified.

• Kyungpook Mathematical Journal
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• v.60 no.4
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• pp.853-867
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• 2020

The aim of this study was to analyze the momentum and heat transfer of a rotating nanofluid with conducting spherical dust particles. The fluid flows over a stretching surface under the influence of an external magnetic field. By applying similarity transformations, the governing partial differential equations were trans-formed into nonlinear coupled ordinary differential equations. These equations were solved with the built-in function bvp4c in MATLAB. Moreover, the effects of the rotation parameter ω, magnetic field parameter M, mass concentration of the dust particles α, and volume fraction of the nano particles 𝜙, on the velocity and temperature profiles of the fluid and dust particles were considered. The results agree well with those in published papers. According to the result the hikes in the rotation parameter ω decrease the local Nusselt number, and the increasing volume fraction of the nano particles 𝜙 increases the local Nusselt number. Moreover the friction factor along the x and y axes increases with increasing volume fraction of the nano particles 𝜙.