A5008549214- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Color Science and Applications
- Astronomy and Astrophysical Research
- Visual perception and processing mechanisms
- Color perception and design
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Electrospun Nanofibers in Biomedical Applications
- Image and Video Quality Assessment
- Membrane Separation Technologies
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Particle physics theoretical and experimental studies
- Advanced Sensor and Energy Harvesting Materials
- Gamma-ray bursts and supernovae
- Solar-Powered Water Purification Methods
- Graphene research and applications
- Advanced Cellulose Research Studies
- Membrane-based Ion Separation Techniques
- Membrane Separation and Gas Transport
- Advanced Optical Imaging Technologies
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
Korea Astronomy and Space Science Institute
2009-2024
Samsung (South Korea)
2008-2024
Sejong University
2015-2021
Institute of Astronomy and Astrophysics, Academia Sinica
2011-2021
National Institute of Environmental Research
2021
Robert Bosch (Germany)
2020
Weatherford College
2020
Government of the Republic of Korea
2020
Samsung (United States)
2016
Northwestern University
2011
Transition metal oxides used as electrode materials for flexible supercapacitors have attracted huge attention due to their high specific capacitance and surface-to-volume ratio, specifically cobalt oxide (Co<sub>3</sub>O<sub>4</sub>) nanoparticles.
We investigate the gravitational wake due to, and dynamical friction on, a perturber moving on circular orbit in uniform gaseous medium using semianalytic method. This work is straightforward extension of Ostriker, who studied case straight-line trajectory. The causes bending background along orbit, forming long trailing tail. distribution thus asymmetric, giving rise to drag forces both opposite (azimuthal) lateral (radial) directions motion perturber, although latter does not contribute...
Abstract— The photogeneration of singlet oxygen ( 1 O 2 ) from thylakoids and the chromophores involved as endogenous sensitizers were investigated using chloroplasts isolated spinach. blue light‐induced inhibition kinetics photosynthetic electron transport that CTvCF, ATPase also studied. spectral dependence generation thylakoid membranes, measured by imidazole plus RNO method, clearly demonstrated Fe‐S centers play an important role in generation, acting thylakoids. photoinhibition was...
We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on time evolution dilepton yields in Upsilon(4S) decays. The measurement is 5.9 fb(-1) data sample collected by Belle detector at KEKB. proper-time difference distributions for same-sign and opposite-sign events are simultaneously fitted to an expression containing as free parameter. Using both muons electrons, we obtain = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This first from measurements Upsilon(4S)....
Observations of increasingly higher spatial resolution reveal the existence asymmetries in circumstellar envelopes a small fraction asymptotic giant branch (AGB) stars. Although there is no general consensus for their origin, binary companion star may be responsible. Within this framework, we investigate gravitational effects associated with sufficiently wide system, where Roche lobe overflow unimportant, on outflowing AGB stars using three-dimensional hydrodynamic simulations. The due to...
Abstract The circumstellar envelope of the carbon star CW Leo exhibited various unexpected changes in recent optical imaging observations. We have performed a follow-up observation using Near-infrared Integral-Field Spectrograph (NIFS) equipped on Gemini-North telescope. report near-infrared counterparts local brightness peak at stellar position Leo. On other hand, second detected short wavelengths J band coincides with brightest, bluest images. absorption features K are minimized radius 0...
We present near-infrared coronagraphic imaging polarimetry of RY Tau. The scattered light in the circumstellar environment was imaged at H-band a high resolution (~0".05) for first time, using Subaru-HiCIAO. observed polarized intensity (PI) distribution shows butterfly-like bright emission with an angular scale similar to disk millimeter wavelengths. This is offset toward blueshifted jet, indicating presence geometrically thick or remnant envelope, and therefore earliest stage Class II...
In many astrophysical situations, as in the coalescence of supermassive black hole pairs at gas-rich galactic nuclei, dynamical friction experienced by an object is a combination its own wake well wakes companion. Using semianalytic approach, we investigate composite due to, and resulting drag forces on, double perturbers that are placed opposite sides orbital center move on circular orbit uniform gaseous medium. The makes each perturber asymmetric, creating overdense tail trailing side. not...
Using high-resolution, two-dimensional hydrodynamic simulations, we investigate nonlinear gravitational responses of gas to, and the resulting drag force on, a very massive perturber M_p moving at velocity V_p through uniform gaseous medium adiabatic sound speed a_0. We model as Plummer potential with softening radius r_s, run various models differing A=GM_p/(a_0^2 r_s) M=V_p/a_0 by imposing cylindrical symmetry respect to line motion. For supersonic cases, quickly develops flows that...
With the advent of high-resolution high-sensitivity observations, spiral patterns have been revealed around several asymptotic giant branch (AGB) stars. Such can provide possible evidence for existence central binary stars embedded in outflowing circumstellar envelopes. Here, we suggest viability explaining previously observed incomplete ring-like with spiral-shell structure as being due to motion (unknown) components viewed at an inclination respect orbital plane. We describe a method...
The binary characteristics of asymptotic giant branch (AGB) stars are imprinted in the asymmetric patterns their circumstellar envelopes. We develop a simple method for constraining orbital parameters such from spiral-like pattern observed at large distances central stars. place constraints on properties AFGL 3068 (i.e., masses components, viewing inclination plane, as well period, velocity, and separation). In particular, mass companion star is estimated to be greater than 2.6 solar mass....
CIT 6 is a carbon star in the transitional phase from asymptotic giant branch (AGB) to protoplanetary nebulae (pPNs). Observational evidences of two point sources optical, circumstellar arc segments an HC3N line emission, and bipolar nebula near-infrared provide strong support for presence binary companion. Hence, very attractive studying role companions AGB–pPN transition. We have carried out high-resolution 12CO J = 2–1 13CO observations with Submillimeter Array combined Telescope...
The morphological properties of the outflowing circumstellar envelopes surrounding mass-losing stars in eccentric binary systems are presented from a set three-dimensional hydrodynamical model simulations. Based on four template models envelope viewed for range inclination angles systems, we implement interpretative tools observations at high spectral/angular resolutions (as illustrated via velocity channel maps as well position-velocity, radius-velocity, and angle-radius diagrams). Within...
Recent observations of strikingly well-defined spirals in the circumstellar envelopes asymptotic giant branch (AGB) stars point to existence binary companions these objects. In case planet- or brown-dwarf-mass companions, we investigate observational properties spiral-onion shell wakes due gravitational interaction with outflowing matter. Three-dimensional hydrodynamical simulations at high resolution show that substellar mass objects produce detectable signatures, corresponding density...
We developed a novel and easy encapsulation method for quantum dots (QDs) using partially oxidized semi-crystalline polymeric material which forms micron-sized granule with multi-lamellar structure from dilute solution. The QDs were highly dispersed in the such way that they adsorbed on lamella ∼12 nm spacing followed by lamellar stacking. heavily loaded into to 16.7 wt% without aggregation, process took only few minutes. found yield of was not degraded after encapsulation. encapsulated...
We fabricated a magnetite nanoparticle-graphene oxide (GO) hybrid via non-chemical and one-step process assisted by ultrasound in an aqueous solution where the nanoparticle attached to hydrophobic region on graphite (multi-layered GO) which, at same time, was exfoliated. Unlike chemical methods such as precipitation, oxygen-containing functional groups GO have not been consumed or reduced during hybridization, leading that this exhibited good water solubility high adsorption capacity for...
We have performed an On-The-Fly (OTF) mapping survey of ${\rm ^{12}{CO(J=1-0)}}$ emission in 28 Virgo cluster spiral galaxies using the Five College Radio Astronomy Observatory (FCRAO) 14-m telescope. This aims to characterize CO distribution, kinematics, and luminosity a large sample covering full extents stellar disks, rather than sampling only inner disks or major axis as was done by many previous single dish interferometric surveys. is detected 20 among spirals observed. An atlas...
The reject water from anaerobic digestion with high (Total Nitrogen) TN concentration was treated by a demonstration plant combining the anammox process and SOD (SOD®; Sulfur Oxidation Denitrification) process. co-digestion of livestock wastewater, food waste water, sewage sludge so that conductivity were very high. This first in South Korea. maximum removal efficiency 80% achieved for reactor under nitrogen loading rate (NLR) 0.45 kg-N/m3·d. As result decreasing dilution influent NLR values...
The accretion process in a typical S-type symbiotic star, targeting~AG Draconis, is investigated through 3D hydrodynamical simulations using the FLASH code. Regardless of wind velocity giant an disk surrounding white dwarf always formed. In models faster than orbital dwarf, size and rate are consistent with predictions under Bondi-Hoyle-Lyttleton (BHL) condition. slower models, unlike BHL predictions, does not grow increases to considerably higher level, up $>20\%$ mass-loss star. our...
In this paper, we introduce a new CDAC architecture suitable for mobile applications.
We have developed stable chitosan colloids over a wide pH range without cross-linkers or gelling agents. The colloid was prepared using nanoparticle obtained from pulverization of bulk powder, followed by surface treatment small amount ascorbic acid (AA) and polyglycerol monostearate (PGMS) in water. Chitosan nanoparticles were well dispersed diluted AA solution due to the protonation chain on surface. And then, addition PGMS led them exhibit highly dispersion even alkali conditions 50 °C....
An orbiting object in a gas rich environment creates gravitational density wake containing information about the and its orbit. Using linear perturbation theory, we analyze observable properties of due to circularly moving static homogeneous gaseous medium, order derive Bondi accretion radius $r_B$, orbital distance $r_p$, Mach number object. Supersonic motion, producing spiral-onion shell structure, exhibits single-armed Archimedes spiral two-centered circular arcs with respect line sight....