• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.114-127
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• 1998

A user friendly computer code(EMCOMST; Electro-Magnetic response for COMposite STructures) was developed which provides with computations of the response characteristics such as reflectance and transmittance to the incident wave angles, frequencies, composite thicknesses, ply orientations, and types of backplate as the linearly polarized transverse electro-magnetic wave is emitted to the advanced composite structures. In this investigation were reviewed the electromagnetic characteristics of the continuous orthotropic fiber-reinforced organic matrix composites with or without ferrite fillers, which are actively applied to low-weight and high-strength aircraft structures. Also were calculated the response of the three layered compound structures which have appropriately stacked above-mentioned materials as transmitting layer, absorbing layer, reflection layer, respectively under the specific thickness constraints for mechanical strength design requirements. For the composite structures presented in this study, minimum reflectance value less than -5㏈ can be obtained in the frequency range of 4 to 12 ㎓. In addition, analysis of structures attached isotropic radar absorbing materials(RAM) is facilitated by putting the material properties in the material input card entries adequately.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1391-1392
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• 1997

The thin films of $\alpha$-Sexithiophene($\alpha$-6T) were deposited by Organic Molecular Beam Deposition(OMBD) technique. The $\alpha$-6T was synthesized and Purified by the sublimation method The thin films of the $\alpha$-6T were deposited under various deposition conditions. The effects of deposition rate substrate temperature, and vacuum pressure on the formation of these films have been studied. The molecular orientations of $\alpha$-6T films were investigated with the polarized electronic absorption spectroscopy. The molecules in the $\alpha$-6T film deposited at a low deposition rate under a high vacuum were almost aligned Perpendicular to the substrate. The film deposited at an elevated substrate temperature(${\sim}90^{\circ}C$) showed higher conductivity than deposited at room temperature.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2895-2899
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• 2013

Direction of intercalation to DNA of the planar dipyrido[3,2-a:2',3'-c]phenazine ligands (dppz) of a bis-Ru(II) complex namely, $[Ru(1,10-phenanthroline)_2dipyrido[3,2-a:2^{\prime},3^{\prime}-c]phenazine]^{2+}$ linkered by a 1,3-bis(4-pyridyl)propane, was investigated by probing the behavior of 4',6-diamidino-2-phenylindole (DAPI) that bound deep in the minor groove. Bis-intercalation of DPPZ resulted in a little blue shift and hyperchromism in DAPI absorption band, and a large decrease in DAPI fluorescence intensity which accompined by an increase in the dppz emission intensity. Diminishing the intenisty of the positive induced circular dichroism (CD) and linear dichroism (LD) were also observed. These spectral changes indicated that insertion of dppz ligand caused the change of the binding mode of DAPI, which probably moved to the exterior of DNA from the minor groove and interacted with the phospghate groups of DNA by electrostatic interaction. At the surface of DNA, DAPI binds at the phosphate groups of DNA by electrostatic attraction. Consequently, this observation indicated that the dppz ligand intercalated from the minor groove.

• Journal of Information Display
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• v.4 no.2
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• pp.29-34
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• 2003

We have studied liquid crystal (LC) molecular alignment on rubbed and photoaligned surfaces. Particular attention was paid to the intermolecular liquid crystalline interaction. We will first show that uniform molecular orientation on a rubbed surface does not mean spatially uniform interaction between the surface and LC molecules. Rather LCs tend to align themselves through LC interaction. The existence of nonuniformity of rubbing was successfully visualized by double surface treatment. The importance of intermolecular LC interaction was also found in the orientation formation process in 5CB evaporated on rubbed and photoaligned surfaces. By simultaneously analyzing polarized UVNIS absorption and second-harmonic generation (SHG) using the maximum entropy method, we succeeded in obtaining the temporal variation of the orientational distribution functions in the film forming process. The distribution anisotropy and pretilt are found to be generated under the influence of intermolecular LC interaction.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.285-289
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• 2000

It has been well known that weak axial magnetic field on the process plasma enhances plasma density. As the magnetic field helps a specific polarized EM wave mode to penetrate into the plasma, the energy transfer to the plasma enhances and the ion density increases. We have analyzed systematic change of the dispersion relation caused by the cyclotron resonance condition. This resonance occurs at near 5 gauss to provide minimum penetration depth, as known before. RF penetration depth increases abruptly beyond the magnetic field of 5 gauss, and this phenomena lessen as the collision frequency increases.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.312-312
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• 2012

Magnesium oxide has become focus for research activities due to its use in magnetic tunnel junctions and for understanding of do ferromagnetism. Theoretical investigations on such type of system indicate that the presence of defects greater than a threshold value is responsible for the magnetic behaviour. It has also been shown experimentally that by decreasing the film thickness and size of nanoparticles, enhancement/increase in magnetization can be achieved. Apart from the change in dimension, swift heavy ions (SHI) are well known for creating defects and modifying the properties of the materials. In the present work, we have studied the irradiation induced effects in magnesium oxide thin film deposited on quartz substrate via X-ray absorption spectroscopy (XAS). Magnesium oxide thin films of thickness 50nm were deposited on quartz substrate by using e-beam evaporation method. These films were irradiated by 200 MeV Ag15+ ion beam at fluence of $1{\times}10^{11}$, $5{\times}10^{11}$, $1{\times}10^{12}$, $3{\times}10^{12}$ and $5{\times}10^{12}ions/cm^2$ at Nuclear Science Centre, IUAC, New Delhi (India). The grain size was observed (as studied by AFM) to be decreased from 37 nm (pristine film) to 23 nm ($1{\times}10^{12}ions/cm^2$) and thereafter it increases upto a fluence of $5{\times}10^{12}ions/cm^2$. The electronic structure of the system has been investigated by X-ray absorption spectroscopy (XAS) measurements performed at the high energy spherical grating monochromator 20A1 XAS (HSGM) beamline in the National Synchrotron Radiation Research Center (NSRRC), Taiwan. Oxides of light elements like MgO/ZnO possess many unique physical properties with potentials for novel application in various fields. These irradiated thin films are also studied with different polarization (left and right circularly polarized) of incident x-ray beam at 05B3 EPU- Soft x-ray scattering beamline of NSRRC. The detailed analysis of observed results in the wake of existing theories is discussed.

• Journal of the Korean Chemical Society
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• v.34 no.5
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• pp.404-412
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• 1990

The time resolved electron spin resonance spectroscopy are used to two measurement methods of chemically induced dynamic electron polarization (CIDEP) and absorption ESR. The spectra of the semiquinone radical anion were successively detected in the laser flash photolysis of anthraquinone in the mixtures of 2-propanol and triethylamine. The semiquinone radical anion was fairly stable and its cw ESR could be observed. The rate constant (T1$^{-1}$) of the spin-depolarization of polarized semiquinone radical anion was 2.6 ${\times}\;1-^5$ sec$^{-1}$ and the decay of the radical anion was the first order with the rate constant (K$_1}$) of 300.0 sec$^{-1}$. The intensity of CIDEP spectra increased with the increasing the microwave power, but the Torrey wiggles appeared following with decay curves.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.3
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• pp.131-138
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• 2002

Thanks to recent progress in availability of molecular and functional techniques it became possible to search for the basic molecular and cellular processes that mediate and control $HCO_3{^-}$ and fluid secretion by the pancreatic duct. The coordinated action of various transporters on the luminal and basolateral membranes of polarized epithelial cells mediates the transepithelial $HCO_3{^-}$ transport, which involves $HCO_3{^-}$ absorption in the resting state and $HCO_3{^-}$ secretion in the stimulated state. The overall process of HCO3 secretion can be divided into two steps. First, $HCO_3{^-}$ in the blood enters the ductal epithelial cells across the basolateral membrane either by simple diffusion in the forms of $CO_2$ and $H_2O$ or by the action of an $Na^+-coupled$ transporter, a $Na^+-HCO_3$ cotranporter (NBC) identified as pNBC1. Subsequently, the cells secrete $HCO_3{^-}$ to the luminal space using at least two $HCO_3{^-}$ exit mechanisms at the luminal membrane. One of the critical transporters needed for all forms of $HCO_3{^-}$ secretion across the luminal membrane is the cystic fibrosis transmembrane conductance regulator (CFTR). In the resting state the pancreatic duct, and probably other $HCO_3{^-}$ secretory epithelia, absorb $HCO_3{^-}.$ Interestingly, CFTR also control this mechanism. In this review, we discuss recent progress in understanding epithelial $HCO_3{^-}$ transport, in particular the nature of the luminal transporters and their regulation by CFTR.

• Proceedings of the Korean Magnestics Society Conference
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• 2011.06a
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• pp.129-129
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• 2011

The limited understanding of the surface properties of $Pt_3Ni$ for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cell (PEMFC) has motivated the study of properties and electronic structures of seven layered $Pt_3Ni$ (001), (110), and (111) surfaces. The first principle method based on density functional theory (DFT) is carried out. It is found that the bulk $Pt_3Ni$ has a ferromagnetic ground state with the ordered fcc type L12 structure, which is in good agreement with other results. Non magnetic Pt has the induced magnetic moment due to the strong hybridization between 3d Ni and 5d Pt. The magnetic moment of Pt and Ni enhanced on the surface of each due to surface effect however the magnetic moment of surface Pt in the Pt-segregated Pt3Ni (111) decreased and the magnetic moment of Ni in Ni rich subsurface increased significantly. The calculated d band centers of Pt explain the possibilities for oxygen absorption and play the important roles in altering the catalytic properties. The spin polarized densities of states are presented in order to understand physical properties of Pt in different surfaces in detail.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.66.2-66.2
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• 2017

The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administrative (NASA) and install it on the International Space Station (ISS). The coronagraph is an externally occulted one stage coronagraph with a field of view from 2.5 to 15 solar radii. The observation wavelength is approximately 400 nm where strong Fraunhofer absorption lines from the photosphere are scattered by coronal electrons. Photometric filter observation around this band enables the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with the high time cadence (< 12 min) of corona images to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in 2017 August for the filter system and to perform a stratospheric balloon experiment in 2019 for the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g. coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.