• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.183-188
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• 1998

A quartz crystal analyzer is utilized to monitor the cmsion process of an aluminum surface of a quartz crystal by sea water. A quartz crystal having 2000${\AA}$ of aluminum layer is installed in a spedally designed cell and is in contact with an electrolyte solution. While a constant potential is applied to the cell, the resonant frequency and resonant resistance are simultaneously measured using the quartz crystal analyzer. In addition, surface topographs are taken with an atomic force microscope(AFM) and the element analysis of the surface is conducted using an energy dispersive X-ray spectrornetedEDX). The simultaneous measurement of resonant frequency and resonant resistance during the corrosion process explains the change of surface structure caused by the corrosion. The variation of resonant frequency addresses the amount surface metal dissolution. As a conclusion, it is found that a simple measurement using the quartz crystal analyzer can replace the complex monitoring employing large equipments in the investigation of a corrosion process of metal surface.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1157-1161
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• 2008

2,6-Dinitrophenol (2,6-DNP) complexes with lanthanide series including yttrium (except Pm, Tm, and Lu) have been synthesized and their crystal structures have been analyzed by X-ray diffraction methods. Singlecrystal X-ray structure determinations have been performed at 296 K on the Ce$\rightarrow$Yb species and shown them to be isomorphous, triclinic, P1, a = 8.6558(2)$\rightarrow$8.5605(3) $\AA$, b = 11.8813(3)$\rightarrow$11.6611(4) $\AA$, c = 13.9650(3) $\rightarrow$13.8341(5) $\AA$, $\alpha$ = 73.785(1)$\rightarrow$73.531(2)o, $\beta$ = 74.730(1)→74.903(2)${^{\circ}}$, $\gamma$ = 69.124(1)→ 69.670 $(2){^{\circ}}$, V = 1266.86(5)→1221.53(7) $$\AA^{3}$$, Z = 2. In Ln(III) complexes, three 2,6-DNP ligands coordinate directly to the metal ion in the bidentate fashion. The nine coordinated Ln(III) ion forms slightly distorted tri-capped trigonal prism. There are no water molecules in the crystal lattice. The dependences of metal to ligand bond lengths are discussed on the atomic number of lanthanide elements. The thermal properties of lanthanide complexes of 2,6- DNP have also studied by TG-DTG and DSC thermal analysis methods.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2299-2304
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• 2012

Two new metal(II) complexes, $[Mn(dpa)(phen)(H_2O)_2]_n$ (1) ($H_2dpa$ = dephenic acid, phen = 1,10-phenanthroline) and $[Ni_2(nda)(phen)_2(H_2O)_6](nda)(H_2O)$ (2) ($H_2nda$ = 2,6-naphthalenedicarboxylic acid) have been synthesized and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single crystal X-ray diffraction. In complex 1, Mn(II) ion is six-coordinated, and Mn(II) ions are bridged by dpa ligands into 1D chains. While, the complex 2 is dimer and two Ni(II) ions are bridged by one nda ligand cooperated with the terminal ligand phen. In each complex, the dicarboxylate ligand is coordinated to metal(II) ions as a bis-monodentate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.12
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• pp.1057-1062
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• 2008

The ${\alpha}-In_2S_3:Co^{2+}$ single crystal with a good quality and stabilized property were gained successfully by the CTR(Chemical Transport Reaction)method. XRD analysis showed that the grown single crystals were cubic structure. The optical absorption spectra of ${\alpha}-In_2S_3:Co^{2+}$ single crystal showed impurity absorption peaks due to cobalt impurity. These impurity absorption pesks were assigned to the ligand transition between the split energy levels of $Co^{2+}$ ions sited in $T_d$ symmetry of these semiconductor host lattice.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.220-221
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• 1999

Single crystals of Yttrium Calcium Oxyborate (YCOB) doped with different concentrations of Er3+ and Yb3+ ions were growth by Czochralski method. High qualities of crystals in morphology and transparency were obtained . Analysis on crystal structure and lattice parameters were performed by X-ray diffraction method. It was found that congruent melting composition is YCA4.2O1.2(BO3)3. Absorption and fluorescence properties of grown crystals were also reported.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.251-252
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• 2012

Recently, the growing interest in organic microelectronic devices including OLEDs has led to an increasing amount of research into their many potential applications in the area of flexible electronic devices based on plastic substrates. However, these organic devices require a gas barrier coating to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency OLEDs require an extremely low Water Vapor Transition Rate (WVTR) of $1{\times}10^{-6}g/m^2$/day. The Key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required ($1{\times}10^{-6}g/m^2$/day) is the suppression of defect sites and gas diffusion pathways between grain boundaries. In this study, we developed an $Al_2O_3$ nano-crystal structure single gas barrier layer using a Neutral Beam Assisted Sputtering (NBAS) process. The NBAS system is based on the conventional RF magnetron sputtering and neutral beam source. The neutral beam source consists of an electron cyclotron Resonance (ECR) plasma source and metal reflector. The Ar+ ions in the ECR plasma are accelerated in the plasma sheath between the plasma and reflector, which are then neutralized by Auger neutralization. The neutral beam energies were possible to estimate indirectly through previous experiments and binary collision model. The accelerating potential is the sum of the plasma potential and reflector bias. In previous experiments, while adjusting the reflector bias, changes in the plasma density and the plasma potential were not observed. The neutral beam energy is controlled by the metal reflector bias. The NBAS process can continuously change crystalline structures from an amorphous phase to nano-crystal phase of various grain sizes within a single inorganic thin film. These NBAS process effects can lead to the formation of a nano-crystal structure barrier layer which effectively limits gas diffusion through the pathways between grain boundaries. Our results verify the nano-crystal structure of the NBAS processed $Al_2O_3$ single gas barrier layer through dielectric constant measurement, break down field measurement, and TEM analysis. Finally, the WVTR of $Al_2O_3$ nano-crystal structure single gas barrier layer was measured to be under $5{\times}10^{-6}g/m^2$/day therefore we can confirm that NBAS processed $Al_2O_3$ nano-crystal structure single gas barrier layer is suitable for OLED application.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.164-170
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• 2000

Neutron single crystal and powder diffraction techniques have been applied to the structure analysis of yttria-stabilized zirconium, Z $r_{0.73}$ $Y_{0.27}$ $O_{1.87}$., prepared by the skull-melting method. The crystal structure has been determined to be cubic symmetry, space group Fm/equation omitted/ with a=5.155(2)$\AA$, V=136.99(5)$\AA$, Z=4, and R(F)=5.65%, $\omega$R(I)=10.57% for 70 integrated intensities of Bragg Peaks observed from single crystal of Z $r_{0.73}$ $Y_{0.27}$ $O_{1.87}$. The stabilizer atoms randomly occupy the zirconium sites and there are displacements of oxygen atoms with amplitudes of $\Delta$/a~0.033 and 0.11 along <110> and <100> directions from the ideal positions of the fluorite structure, respectively. There are no significant differences in crystallographic data between the single crystal and powder studies. Diffraction pattern after Rietveld refinement, using neutron powder data, has shown the evidence of a tetragonal impurity phase, or a slight tetragonal distortion.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.16-24
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• 2022

A computational study of combined thermal and solutal convection (double diffusive convection) in a sealed crystal growth reactor is presented, based on a two-dimensional numerical analysis of the nonlinear and strongly coupled partial differential equations and their associated boundary conditions. The average Nusselt numbers for the source regions are greater than those at the crystal regions for 9.73 × 10³ ≤ Gr_t ≤ 6.22 × 10⁵. The average Nusselt numbers for the source regions varies linearly and increases directly with the thermal Grashof number form 9.73 × 10³ ≤ Gr_t ≤ 6.22 × 10⁵ for aspect ratio, Ar (transport length-to-width) = 1 and 2. Additionally, the average Nusselt numbers for the crystal regions at Ar = 1 are much greater than those at Ar = 2. Also, the occurrence of one unicellular flow structure is caused by both the thermal and solutal convection, which is inherent during the physical vapor transport of Hg₂Br₂. When the aspect ratio of the enclosure increases, the fluid movement is hindered and results in the decrease of thermal buoyancy force.

• Molecules and Cells
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• v.43 no.12
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• pp.1035-1045
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• 2020

The Drosophila genome contains four low molecular weight-protein tyrosine phosphatase (LMW-PTP) members: Primo-1, Primo-2, CG14297, and CG31469. The lack of intensive biochemical analysis has limited our understanding of these proteins. Primo-1 and CG31469 were previously classified as pseudophosphatases, but CG31469 was also suggested to be a putative protein arginine phosphatase. Herein, we present the crystal structures of CG31469 and Primo-1, which are the first Drosophila LMW-PTP structures. Structural analysis showed that the two proteins adopt the typical LMW-PTP fold and have a canonically arranged P-loop. Intriguingly, while Primo-1 is presumed to be a canonical LMW-PTP, CG31469 is unique as it contains a threonine residue at the fifth position of the P-loop motif instead of highly conserved isoleucine and a characteristically narrow active site pocket, which should facilitate the accommodation of phosphoarginine. Subsequent biochemical analysis revealed that Primo-1 and CG31469 are enzymatically active on phosphotyrosine and phosphoarginine, respectively, refuting their classification as pseudophosphatases. Collectively, we provide structural and biochemical data on two Drosophila proteins: Primo-1, the canonical LMW-PTP protein, and CG31469, the first investigated eukaryotic protein arginine phosphatase. We named CG31469 as DARP, which stands for Drosophila ARginine Phosphatase.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1021-1025
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• 2009

A novel supramolecular network containing binuclear copper unit $[Cu(phen)_{2}({\mu}-ID\;A)Cu(phen){\cdot}(NO_{3})](NO_{3}){\cdot}4(H_{2}O)$ (1) was synthesized through the self-assembly of iminodiacetic acid ($H_2IDA$) and 1,10-phenanthroline (phen) in the condition of pH = 6. It has been characterized by the infrared (IR) spectroscopy, elemental analysis, single crystal X-ray diffraction, and thermogravimetric analysis (TGA). 1 shows a 2-D supramolecular structure assembled through strong and unique $\pi-\pi$ packing interactions. Density functional theory (DFT) calculations show that theoretical optimized structures can well reproduce the experimental structure. The TGA and powder X-ray diffraction (PXRD) curves indicate that the complex 1 can maintain the structural integrity even at the loss of free water molecules. The magnetic property is also reported in this paper.