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Search Results: 1 - 10 of 50082 matches for " Yong-Hyun Lee "
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The Graduate Law Degree Holders in the Legal Education Market: Evidence from the US, Rankings and Implications  [PDF]
Kiyoung Kim, Shahin Borhanian, Koo-Tae Chung, Yong-Hyun Park, Won-Sang Lee, Jae-Hyung Kim
Beijing Law Review (BLR) , 2016, DOI: 10.4236/blr.2016.74031
Abstract: Given that the law is helpful, essential and non-separable with our lives, we surely would like to know the people that make laws and who practice in the legal profession. This query is the recent theme we have pursued in this and other related projects. The investigation has revealed a knowledge economy (savoir-faire) that has entwined law and the actions of law people, which growingly became edged to explain their behavior and moral and professional conduct. The expectation has been that graduate law classes are for foreign lawyers who would return to their home country to work as international lawyers or as professors. That has long been deemed as a given; but the precise reality has not been previously unraveled. With this backdrop, the current paper purports to survey the status and performance of graduate law degree holders in US law school, to rank global law schools, and explore the implications and findings concerning the processes and outcomes of their missions.
Near-Infrared Spectroscopy of Young Galactic Supernova Remnants
Bon-Chul Koo,Yong-Hyun Lee
Physics , 2015,
Abstract: Young Galactic supernova remnants (SNRs) are where we can observe closely the supernova (SN) ejecta and its interaction with circumstellar/interstellar medium. Therefore, they provide an opportunity to explore the explosion and the final stage of the evolution of massive stars. Near-infrared (NIR) emission lines in SNRs mostly originate from shocked dense material. In shocked SN ejecta, forbidden lines from heavy ions are prominent, while in shocked circumstellar/interstellar medium, [Fe II] and H2 lines are prominent. [Fe II] lines are strong in both media, and therefore [Fe II] line images provide a good starting point for the NIR study of SNRs. There are about twenty SNRs detected in [Fe II] lines, some of which have been studied in NIR spectroscopy. We will review the NIR [Fe II] observations of SNRs and introduce our recent NIR spectroscopic study of the young core-collapse SNR Cas A where we detected strong [P II] lines.
Dynamics of fullerene coalescence
Yong-Hyun Kim,In-Ho Lee,K. J. Chang,Sangsan Lee
Physics , 2002, DOI: 10.1103/PhysRevLett.90.065501
Abstract: Fullerene coalescence experimentally found in fullerene-embedded single-wall nanotubes under electron-beam irradiation or heat treatment is simulated by minimizing the classical action for many atom systems. The dynamical trajectory for forming a (5,5) C$_{120}$ nanocapsule from two C$_{60}$ fullerene molecules consists of thermal motions around potential basins and ten successive Stone-Wales-type bond rotations after the initial cage-opening process for which energy cost is about 8 eV. Dynamical paths for forming large-diameter nanocapsules with (10,0), (6,6), and (12,0) chiral indexes have more bond rotations than 25 with the transition barriers in a range of 10--12 eV.
Near-infrared Extinction due to Cool Supernova Dust in Cassiopeia A
Yong-Hyun Lee,Bon-Chul Koo,Dae-Sik Moon,Jae-Joon Lee
Physics , 2015, DOI: 10.1088/0004-637X/808/1/98
Abstract: We present the results of extinction measurements toward the main ejecta shell of the Cassiopeia A supernova (SN) remnant using the flux ratios between the two near-infrared (NIR) [Fe II] lines at 1.26 and 1.64 $\mu {\rm m}$. We find a clear correlation between the NIR extinction ($E(J-H)$) and the radial velocity of ejecta knots, showing that redshifted knots are systematically more obscured than blueshifted ones. This internal "self-extinction" strongly indicates that a large amount of SN dust resides inside and around the main ejecta shell. At one location in the southern part of the shell, we measure $E(J-H)$ by the SN dust of 0.23$\pm$0.05 mag. By analyzing the spectral energy distribution of thermal dust emission at that location, we show that there are warm ($\sim$100 K) and cool ($\sim$40 K) SN dust components and that the latter is responsible for the observed $E(J-H)$. We investigate the possible grain species and size of each component and find that the warm SN dust needs to be silicate grains such as MgSiO$_{3}$, Mg$_{2}$SiO$_{4}$, and SiO$_{2}$, whereas the cool dust could be either small ($\leq$0.01 $\mu {\rm m}$) Fe or large ($\geq$0.1 $\mu {\rm m}$) Si grains. We suggest that the warm and cool dust components in Cassiopeia A represent grain species produced in diffuse SN ejecta and in dense ejecta clumps, respectively.
Seebeck effect at the atomic scale
Eui-Sup Lee,Sanghee Cho,Ho-Ki Lyeo,Yong-Hyun Kim
Physics , 2013, DOI: 10.1103/PhysRevLett.112.136601
Abstract: The atomic variations of electronic wavefunctions at the surface and electron scattering near a defect have been detected unprecedentedly by tracing thermoelectric voltages given a temperature bias [Cho et al., Nature Mater. 12, 913 (2013)]. Because thermoelectricity, or Seebeck effect, is associated with heat-induced electron diffusion, how the thermoelectric signal is related to the atomic-scale wavefunctions and what the role of the temperature is at such a length scale remain very unclear. Here we show that coherent electron and heat transport through a point-like contact produces an atomic Seebeck effect, which is described by mesoscopic Seebeck coefficient multiplied with an effective temperature drop at the interface. The mesoscopic Seebeck coefficient is approximately proportional to the logarithmic energy derivative of local density of states at the Fermi energy. We deduced that the effective temperature drop at the tip-sample junction could vary at a sub-angstrom scale depending on atom-to-atom interaction at the interface. A computer-based simulation method of thermoelectric images is proposed, and a point defect in graphene was identified by comparing experiment and the simulation of thermoelectric imaging.
Phosphorus in the Young Supernova Remnant Cassiopeia A
Bon-Chul Koo,Yong-Hyun Lee,Dae-Sik Moon,Sung-Chul Yoon,John C. Raymond
Physics , 2013, DOI: 10.1126/science.1243823
Abstract: Phosphorus ($^{31}$P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron ($^{56}$Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion.
[Fe II] 1.64 um Imaging Observations of the Outflow Features around Ultracompact H II Regions in the 1st Galactic Quadrant
Jong-Ho Shinn,Kee-Tae Kim,Jae-Joon Lee,Yong-Hyun Lee,Hyun-Jeong Kim,Tae-Soo Pyo,Bon-Chul Koo,Jaemann Kyeong,Narae Hwang,Byeong-Gon Park
Physics , 2014, DOI: 10.1088/0067-0049/214/1/11
Abstract: We present [Fe II] 1.644 um features around ultracompact H II regions (UCHIIs) found on a quest for the "footprint" outflow features of UCHIIs---the feature produced by the outflowing materials ejected during the earlier, active accretion phase of massive young stellar objects (MYSOs). We surveyed 237 UCHIIs in the 1st Galactic quadrant, employing the CORNISH UCHII catalog and UWIFE data which is an imaging survey in [Fe II] 1.644 um performed with UKIRT-WFCAM under ~ 0.8" seeing condition. The [Fe II] features were found around five UCHIIs, one of which is of low plausibility. We interpret that the [Fe II] features are shock-excited by outflows from YSOs, and estimate the outflow mass loss rates from the [Fe II] flux, which are ~ 1 x 10^-6 - 4 x 10^-5 Ms yr^-1. We propose that the [Fe II] features might be the "footprint" outflow features, but more studies are required to clarify it. This is based on the morphological relation between the [Fe II] and 5 GHz radio features, the outflow mass loss rate, the travel time of the [Fe II] features, and the existence of several YSO candidates near the UCHIIs. The UCHIIs accompanying the [Fe II] features have a relatively higher peak flux density. The fraction of UCHIIs accompanying the [Fe II] features, 5/237, is small when compared to the ~ 90 % detection rate of high-velocity CO gas around UCHIIs. We discuss some possible explanations on the low detection rate.
Near-infrared H2 and Continuum Survey of Extended Green Objects. II. Complete Census for the Northern Galactic Plane
Hsu-Tai Lee,Wei-Ting Laio,Dirk Froebrich,Jennifer Karr,Georgios Ioannidis,Yong-Hyun Lee,Yu-Nung Su,Sheng-Yuan Liu,Hao-Yuan Duan,Michihiro Takami
Physics , 2013, DOI: 10.1088/0067-0049/208/2/23
Abstract: We discuss 94 Extended Green Objects (EGOs) in the northern Galactic plane cataloged by Cyganowski et al, based on near-infrared narrowband H2 (2.122 {\mu}m and continuum observations from the United Kingdom Infrared Telescope. This data set is three times larger than our previous study, and is unbiased by preselection. As discussed in the previous paper, the morphologies of the 4.5 {\mu}m emission generally resemble those of the near-infrared continuum, but are different from those of the H2 emission. Of our sample, only 28% of EGOs with H2 emission show similar morphologies between 4.5 {\mu}m and H2 emission. These results suggest that the 4.5 {\mu}m emission mainly comes from scattered continuum from the embedded young stellar object (YSO), and partially from H2 emission. About half of EGOs are associated with H2 outflows, if the H2 outflow incompleteness is considered. The H2 outflow detection rate for EGOs with K-band detections (61%) is significantly higher than for those without K-band detections (36%). This difference may be due to the fact that both H2 and K-band emissions are associated with outflows, i.e., H2 emission and K-band continuum are associated with shocks and outflow cavities, respectively. We also compared the correlation between the H2 outflows and Class I 44 GHz methanol masers from literature. The methanol masers can be located upstream or downstream of the H2 outflows and some bright H2 spots or outflows are not associated with methanol masers, suggesting that methanol masers and H2 emission trace different excitation conditions.
Thermoelectric imaging of structural disorder in epitaxial graphene
Sanghee Cho,Stephen Dongmin Kang,Wondong Kim,Eui-Sup Lee,Sung-Jae Woo,Ki-Jeong Kong,Ilyou Kim,Hyeong-Do Kim,Tong Zhang,Joseph A. Stroscio,Yong-Hyun Kim,Ho-Ki Lyeo
Physics , 2013, DOI: 10.1038/nmat3708
Abstract: Heat is a familiar form of energy transported from a hot side to a colder side of an object, but not a notion associated with microscopic measurements of electronic properties. A temperature difference within a material causes charge carriers, electrons or holes, to diffuse along the temperature gradient inducing a thermoelectric voltage. Here we show that local thermoelectric measurements can yield high sensitivity imaging of structural disorder on the atomic and nanometre scales. The thermopower measurement acts to amplify the variations in the local density of states at the Fermi-level, giving high differential contrast in thermoelectric signals. Using this imaging technique, we uncovered point defects in the first layer of epitaxial graphene, which generate soliton-like domain wall line patterns separating regions of the different interlayer stacking of the second graphene layer.
[Fe II] 1.64 um Features of Jets and Outflows from Young Stellar Objects in the Carina Nebula
Jong-Ho Shinn,Tae-Soo Pyo,Jae-Joon Lee,Ho-Gyu Lee,Hyun-Jeong Kim,Bon-Chul Koo,Hwankyung Sung,Moo Young Chun,A. -Ran Lyo,Dae-Sik Moon,Jaemann Kyeong,Byeong-Gon Park,Hyeonoh Hur,Yong-Hyun Lee
Physics , 2013, DOI: 10.1088/0004-637X/777/1/45
Abstract: We present [Fe II] 1.64 {\mu}m imaging observations for jets and outflows from young stellar objects (YSOs) over the northern part (~ 24'x45') of the Carina Nebula, a massive star forming region. The observations were performed with IRIS2 of Anglo-Australian Telescope and the seeing was ~1.5"+-0.5". Eleven jet and outflow features are detected at eight different regions, and are named as Ionized Fe Objects (IFOs). One Herbig-Haro object candidate missed in Hubble Space Telescope H{\alpha} observations is newly identified as HHc-16, referring our [Fe II] images. IFOs have knotty or longish shapes, and the detection rate of IFOs against previously identified YSOs is 1.4 %, which should be treated as a lower limit. Four IFOs show an anti-correlated peak intensities in [Fe II] and H{\alpha}, where the ratio I([Fe II])/I(H{\alpha}) is higher for longish IFOs than for knotty IFOs. We estimate the outflow mass loss rate from the [Fe II] flux, using two different methods. The jet-driving objects are identified for three IFOs (IFO-2, -4, and -7), for which we study the relations between the outflow mass loss rate and the YSO physical parameters from the radiative transfer model fitting. The ratios of the outflow mass loss rate over the disk accretion rate are consistent for IFO-4 and -7 with the previously reported values (10^-2-10^+1), while it is higher for IFO-2. This excess may be from the underestimation of the disk accretion rate. The jet-driving objects are likely to be low- or intermediate-mass stars. Other YSO physical parameters, such as luminosity and age, show reasonable relations or trends.
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