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Daegu, South Korea

Daegu Health College provides medical training to aspiring professionals in Daegu metropolitan city, South Korea. The current president is Nam Seong-hui . About 100 instructors are employed. Wikipedia.

Choi J.R.,Daegu Health College
Results in Physics | Year: 2013

Quantum energies for Caldirola-Kanai Hamiltonian systems with and without a singular perturbation are investigated in coherent states on the basis of invariant operator theory. Our results are compared with those of several different approaches from various angles. Further, the advantages of our method over that adopted in the previous researches are addressed in detail. © 2013 Elsevier Ltd.V.

An adiabatic invariant, which is a conserved quantity, is useful for studying quantum and classical properties of dynamical systems. Adiabatic invariants for time-dependent superconducting qubit-oscillator systems and resonators are investigated using the Liouville-von Neumann equation. At first, we derive an invariant for a simple superconducting qubit-oscillator through the introduction of its reduced Hamiltonian. Afterwards, an adiabatic invariant for a nanomechanical resonator linearly interfaced with a superconducting circuit, via a coupling with a time-dependent strength, is evaluated using the technique of unitary transformation. The accuracy of conservation for such invariant quantities is represented in detail. Based on the results of our developments in this paper, perturbation theory is applicable to the research of quantum characteristics of more complicated qubit systems that are described by a time-dependent Hamiltonian involving nonlinear terms. © 2015 Jeong Ryeol Choi.

Choi J.R.,Daegu Health College
Physics of the Dark Universe | Year: 2013

Quantum behavior of scalar fields and vacuum energy density in inflationary universe are investigated using SU(1,1) Lie algebraic approach. Wave functions describing the evolution of scalar fields thought to have driven cosmic inflation are identified in several possible quantum states at the early stage of the universe, such as the Fock state, the Glauber coherent state, and SU(1,1) coherent states. In particular, we focus in this research on two important classes of SU(1,1) coherent states, so-called the even and odd coherent states and the Perelomov coherent state. It is shown in spatially flat universe driven by a single scalar field that the probability densities in all these states have converged to the origin (φ? == 0, where φ? is the scalar field) as time goes by. This outcome implies that the vacuum energy density characterized by the scalar field dissipates with time. The probability density in the matter-dominated era converged more rapidly than that in the radiation-dominated era. Hence, we can confirm that the progress of dissipation for vacuum energy density became faster as the matter era began after the end of the early dominance of radiation. This consequence is, indeed, well agree with the results of our previous researches in cosmology (for example, see [Chin. Phys. C 35 (2011) 233] and references there in). © 2013 Jeong Ryeol Choi.

Kim W.-G.,Daegu Health College | Choe H.-C.,Chosun University
Thin Solid Films | Year: 2011

The purpose of this study was to investigate the surface characteristics of hydroxyapatite (HA)/titanium (Ti) composite layer on the Ti-35Ta-xZr alloy surface by radio frequency (RF) and direct current (DC) sputtering for dental application. The magnetron sputtered deposition for the HA was performed in the RF mode and for the Ti in the DC mode. Microstructures of the alloys were examined by optical microscopy (OM) and x-ray diffractometer (XRD). Surface characteristics of coated film was investigated by field-emission scanning electron microscope (FE-SEM) equipped with an energy dispersive x-ray spectrometer (EDS), and XRD. Microstructures of the Ti-35Ta-xZr alloys were changed from α″ phase to β phase, and changed from a needle-like structure to an equiaxed structure with increasing Zr content. From the results of polarization behavior in the Ti-35Ta-15Zr alloy, HA/Ti composite layer showed the good corrosion resistance compared to Ti single layer. The results of alternating current (AC) impedance test indicated that the presence of ha coating acted as a stable barrier in increasing the corrosion resistance. © 2011 Elsevier B.V.

Rooh G.,Kyungpook National University | Kim H.J.,Kyungpook National University | Kim S.,Daegu Health College
IEEE Transactions on Nuclear Science | Year: 2010

In this work, we present the crystal growth and scintillation properties of our newly developed scintillation crystal, Cs2 LiCeCl6, for a γ-ray spectroscopy. This scintillation crystal is grown by using the vertical Bridgman method. The crystal of this material belongs to the elpasolite family characterized by a cubic structure and potentially can be easily grown in large volumes. Under the X-ray excitation, cerium emission band is observed to peak at 385 nm and 405 nm. An energy resolution (full width at half maximum over the peak position) of 5.5 % was observed for the 662 keV full absorption peak. We measured an absolute light yield of 22 000 photons/MeV of absorbed γ-ray energy. The crystal shows three main scintillation decay time components of 101 ns (42%), 557 ns (35%) and 2.9 μs (23%). This material is highly hygroscopic and special attention was paid during data taking and handling processes. We believe that the Cs2 LiCeCl6 crystal can be a promising material for medical imaging and radiation detection. Moreover due to the presence of Li ions, this scintillation crystal can also be a possible candidate for thermal neutron detection. © 2010 IEEE.

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