• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.106-107
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• 2007

We fabricated anodic aluminium oxides (AAO) on Si and sapphire substrates from the electrochemical reactions of thin AI films in an aqueous solution of oxalic acid. The thin AI films have deposited on Si and Sapphire substructure by using E-beam evaporation and thermal evaporation, respectively. The formation of AAO structures has investigated from FE-SEM measurement image and showed randomly distributed phase of nanoholes instead of the periodic lattice of photonic crystals. The AAO structure on sapphire shows the double layers of nanoholes.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1864-1865
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• 2007

In this paper, we proposed pre-filter algorithms which using frequency domain analysis method, for the detections of defects in large-sized Thin Film Transistor-Liquid Crystal Display(TFT-LCD) panel surfaces. We performed frequency analysis with 1-D, 2-D FFT methods for extract periodic patterns of lattice structures in TFT-LCDs. To remove this patterns, band-stop filters were used for eliminating specific frequency components. In order to acquire only defected images, we used 2-D inverse FFT methods which can be reverts images that remains defects.

• Bulletin of the Korean Chemical Society
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• v.5 no.1
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• pp.37-41
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• 1984

The pseudolattice calculations in the CNDO/2 level of approximation are carried out for polymeric beryllium hydride, polyethylene and polymeric boron hydride. Since there is no evidence on the geometry for polymeric boron hydride, the two possible geometries are assumed. One is a polyethylene-type geometry and the other is a polymeric beryllium hydride-type geometry. In order to compare their relative stability, we calculate polyethylene and polymeric beryllium hydride and then compare with polymeric boron hydride having the assumed structures. The total energy calculation indicates that a polymeric beryllium bydride-type geometry is more stable than a polyethylene-type geometry. Our results obtained for polyethylene are in good agreement with those given by CNDO/2 crystal orbital. From the convergence problem with respect to the number of unit cells (M), the calculation with value of 4 for M can be considered to give the convergence limit results.

• Bulletin of the Korean Chemical Society
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• v.17 no.5
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• pp.447-452
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• 1996

Three conformational isomers of calix[4]arene butanoate were isolated from the reaction of calix[4]arene and butanoyl chloride in the presence of NaH and their structures were determined by NMR spectra as 1,2-alternate 2a, partial cone 2b and 1,3-alternate conformer 2c, respectively. The crystal structure of 2a has been determined by X-ray diffraction method. The crystals are monoclinic, space group C2/c, a=18.435 (4), b=13.774 (2), c=16.941 (3) Å, β=116.23 (1)°, Z=4, V=3858.8 (12)Å3, Dc=1.21 g cm-3, Dm=1.21 g cm-3. The molecule is in the 1,2-alternate conformation. It has two-fold symmetry axis along the line connecting between C (7AA') and C (7BB') parallel to the b axis of crystal lattice.

• Journal of Magnetics
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• v.12 no.2
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• pp.68-71
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• 2007

Even a pure bulk Fe has a complicated magnetic phase and its magnetism is still needed to be clarified. In this study we investigated the magnetism of bcc and fcc bulk Fe with total energy calculations as functions of atomic volume. The full-potential linearized augmented plane wave method was adopted within a generalized gradient approximation. The ground state of bulk Fe is confirmed to be of ferromagnetic (FM) bcc. For fcc structured Fe an antiferromagnetic (AFM) state is more stable compared to FM states which exist as low spin and high spin states. The stable AFM states were found to accompany a tetragonal distortion, while the FM states remained in a cubic symmetry. At an expanded lattice constant a high spin FM state was calculated to be able to be stabilized with significant enhanced magnetic moment compared to the value of the ground state, bcc FM.

• Journal of applied mathematics & informatics
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• v.39 no.5_6
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• pp.769-783
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• 2021

Demirci ((1999) Vague groups. J. Math. Anal. Appl. 230, 142-156) introduced the concept of vague groups as one of uncertain reasoning structures where indistinguishable operators separate points. In this paper, we consider vague groups in which an indistinguishable operator does not need to separate points because it seems more appropriate to handle ambiguous situations. For our purposes we generalize or redefine some notions such as: vague closed subset, vague subgroup, vague kernel and vague injectiveness. Consequently we generalize most of the known results and obtain some new additional fundamental properties of vague groups, some of which are similar to ones of ordinary groups.

• Bulletin of the Korean Chemical Society
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• v.6 no.6
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• pp.337-343
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• 1985

A statistical mechanical approach to elucidate the solvent effects on the high polymer solutions has been carried out on the basis of the simple model of liquids improved by Pak. In our works, the partition function of the polymer solutions is formulated by the lattice model and our simple treatment of liquid structures. For the ideal polymer solutions proposed by Flory, thermodynamic functions of the polymer solutions are obtained and equations of mixing properties and partial molar quantities are derived from the presented partition function of the polymer solutions. Partial molar quantities are calculated for the rubber solutions in carbon disulfide, benzene and carbon tetrachloride. Comparisons have been made between our equations and those of Flory's original paper for partial molar properties of the rubber-benzene system. Comparing the experimental data of the osmotic pressure of polystyrene-cyclohexane system with our calculated values and those of Flory's, our values fit to the agreeable degrees better than those of Flory's.

• Bulletin of the Korean Chemical Society
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• v.17 no.2
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• pp.168-172
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• 1996

The variations of the structural detail of layered perovskite-type oxides, Na2Ln2Ti3O10 (Ln=La, Nd, Sm, Gd), have been refined by Rietveld analyses of their powder X-ray diffraction data. Although the c-axis strongly decreases from Ln=La to Nd, Sm, or Gd, the length of Na-O bond along the c-axis that is regarded as the sodium layer spacing is not dependent on the unit cell parameter. Such a behavior is explained by the fact that Na-O bond is in competition with Ti-O one of the perovskite slab. Increased covalency of this Ti-O bond by the lattice contraction leads to weakening of the attaching strength of Na ion. This picture is consistent with the experimental observation that Na ion conductivity of Na2Ln2Ti3O10 increases from Ln=La to Nd, Sm, or Gd despite strong contraction of the unit cell volume.

• Journal of Sericultural and Entomological Science
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• no.11
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• pp.59-62
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• 1970

Many a fine structures of nuclear polyhedrosis virus in Lepidoptera had been described by electron microscope. In the larva of Antheraea pernyi Guerin, the leading virus causing infectious disease in Korea is disclosed nuclear polyhedrosis virus, which embed bundles of virus particles in the molecular lattice of polyhedra protein. The number of virus particles within a bundle. is on the average four particles, which are enclosed in a intimate membrane closely surrounded with developing membrane. The bundles of four virus particlesare at random embedded in the polyhedra protein, which is originated from the so-called virogenic stroma of chromosom in the infected nuclear.

• Journal of Korean Association for Spatial Structures
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• v.11 no.1
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• pp.121-130
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• 2011

Space frame structures have the advantage of constructing a large space structures without column and it may be considered as a shell structure. Nevertheless, with the characteristics of thin and long term of spacing, the unstable problem of space structure could not be set up clearly, and there is a huge difference between theory and experiment. Therefore, in this work, the tangential stiffness matrix of space frame structures is studied to solve the instability problem, and the nonlinear incremental analysis of the structures considering rise-span ratio(${\mu}$) and the ratio of load($R_L$) is performed for searching unstable points. Basing on the results of the example, global buckling can be happened by low rise-span ratio(${\mu}$), nodal buckling can be occurred by high rise-span ratio(${\mu}$). And in case of multi node space structure applying the ratio of load($R_L$), the nodal buckling phenomenon occur at low the ratio of load($R_L$), the global buckling occur a1 high the ratio of load($R_L$). In case of the global buckling, the load of bifurcation is about from 50% to 70% of perfect one's snap-through load.