• Journal of the Korean Chemical Society
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• v.42 no.3
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• pp.292-296
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• 1998

The elution behavior of copper(Ⅱ) and iron(Ⅱ) ions by phenol sulfonic acid(PSA) as an eluent on chelating resin, Amberlite IRC-718 have been investigated. When copper(Ⅱ) and iron(Ⅱ) solutions were adsorbed on the resin and eluted with various concentration of PSA, two peaks of each ion were appeared in the elution curve. These two peak areas were changed according to the PSA concentration. Using these phenomena, the stability constants of complex formation between the two ions and PSA were calculated. The values are 7.0 for copper(II) and $4.5{\times}10^4$ for iron(II), respectively.

• Journal of the Korean Ceramic Society
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• v.55 no.3
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• pp.290-298
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• 2018

In order to investigate the effect of thickness on the dielectric and piezoelectric properties of (001) PMN-29PT single crystals, three different types of PMN-29PT samples were prepared using the solid-state single crystal growth (SSCG) method: high density crystal [99%], low density crystal [95%], and high density crystal doped with Mn [98.5%]. When their thickness decreased from 0.5 mm to 0.05 mm, their dielectric constant ($K_3{^T}$), piezoelectric constants ($d_{33}$ and $g_{33}$), and electromechanical coupling factor ($k_t$) decreased continuously. However, their dielectric loss (tan ${\delta}$) increased. The addition of Mn to PMN-PT induced an internal bias electric field ($E_I$), increased the coercive electric field ($E_C$), and prevented local depoling. Therefore, Mn-doped PMN-PT crystals show high stability as well as high performance, even in the form of very thin plates (< 0.2 mm), and thus are suitable for application to high frequency composites, medical ultrasound probes, non-destructive testing devices (NDT), and flexible devices.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.1951-1955
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• 2009

A Thermodynamic study on the interaction of bovine calf thymus DNA with new designed Pd(II) complex (Ethylendiamine- 8-hydroxyquinolinato Palladium(II) chloride) was studied by using isothermal titration calorimetry (ITC) at 27 ${^{\circ}C}$ in Tris buffer solution at pH = 7.5. The enthalpies of Pd(II) complex + DNA interaction are reported and analysed in terms of the new solvation theory. It was indicated that there are three identical and non-cooperative sites for Pd(II) complex. The binding of a Pd(II) complex is endothermic with association equilibrium constants of 428.03 m$M^{-1}$ at 27 ${^{\circ}C}$. The binding of Pd(II) complex can cause some changes in the stability of the DNA at low and high Pd(II) complex concentrations. Our results suggested that this complex might interact with DNA as an intercalator, thus interfering with DNA replication and cell proliferation.

• Electrical & Electronic Materials
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• v.16 no.9
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• pp.65.1-65
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• 2003

The interface of zirconium oxide thin films on silicon is analyzed in detail for their potential applications in the microelectronics. The formation of an interfacial layer of ZrSi$\sub$x/O$\sub$y. with graded Zr concentration is observed by the x-ray photoelectron spectroscopy and secondary ion mass spectrometry analysis. The as-deposited ZrO$_2$/ZrSi$\sub$x/O$\sub$y//Si sample is thermally stable up to 880$^{\circ}C$, but is less stable compared to the ZrO$_2$/SiO$_2$/Si samples. Post-deposition annealing in oxygen or ammonia improved the thermal stability of as-deposited ZrO$_2$/ZrSi$\sub$x/O$\sub$y/Si to 925$^{\circ}C$, likely due to the oxidation/nitridation of the interface. The as-deposited film had an equivalent oxide thickness of∼13 nm with a dielectric constant of ∼21 and a leakage current of 3.2${\times}$10e-3 A/$\textrm{cm}^2$ at 1.5V. Upon oxygen or ammonia annealing, the formation of SiO$\sub$x/ and SiH$\sub$x/N$\sub$y/O$\sub$z/ at the interface reduced the overall dielectric constants.

• Journal of the Korean Magnetic Resonance Society
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• v.18 no.2
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• pp.52-57
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• 2014

The TCP domain is a DNA-binding domain present in plant transcription factors and plays important roles in various biological functions. The hydrogen exchange rate constants of the imino protons were determined for the three DNA duplexes containing the DNA-binding sites for the TCP11, TCP15, and TCP20 transcription factors using NMR spectroscopy. The M11 duplex displays unique hydrogen exchange property of the five base pairs in the first binding site (5'-GTGGG-3'). However, the M15 and M20 duplexes lead to clear changes in thermal stabilities of these five base pairs. The unique dynamic features of the five base pairs in the first binding site might play crucial roles in the sequence-specific DNA binding of the class I TCP transcription factors.

• Journal of Pharmaceutical Investigation
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• v.13 no.1
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• pp.10-22
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• 1983

The interactions of ${\alpha}-cyclodextrin({\alpha}-CyD)$ and ${\beta}-cyclodextrin({\beta}-CyD)$ with several non-steroidal antiinflammatory drugs were studied on the effects of ${\alpha}-$ and ${\beta}-CyD$ on the solubility of the drugs in aqueous medium. Indoprofen, niflumic acid, alclofenac, and naproxen were chosen as representatives of antiinflammatory drugs. The solubility of all drugs studied increased with the addition of ${\beta}-CyD$, while not with glucose or ${\alpha}-CyD$. The increase of the solubility with ${\beta}-CyD$ was considered due mainly to the formation of inclusion complexes between ${\beta}-CyD$ and drugs. From the solubility data, the apparent stability constants K of the complex could be calculated. Ultraviolet absorption and circular dichroism confirmed the inclusion of indoprofen, niflumic acid and naproxen with ${\beta}-CyD$ in the molar ratio of 1 : 1. Inclusion complexes in solid powder form were obtained by the freeze-drying method and the inclusion formation was confirmed again by infrared, diffential thermal analysis, and X-ray diffraction measurements.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.425-431
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• 1999

$Pb(Zr_{0.52}, Ti_{0.48})O_3$ (PZT) thick films as an actuating material with conducting oxides, $(La_{0.5}Sr_{0.5}) CoO_3$ (LSCO), have been fabricated by sol-gel method for Optical Micro-Electro-Mechanical System (MEMS) devices, in which PZT/LSCO/SiO2 structures were used. In order to improve the adhesion to LSCO solution in order to enhance the wetting behavior of a water-based LSCO precursor solution and further to improve the adhesion between LSCO and $SiO_2$ layers. PZT films were made using 1-3 propanediol based precursor solution which has a high viscosity and a boiling point appropriate for thick film fabrication. In the precursor solution, Ti-propoxied and Zr-propoxied are partially substituted with acetylacetone to achieve the solution stability while maintaining reactivity. Crack free PZT films (0.8~1$\mu\textrm{m}$) have been successfully fabricated at crystallization temperatures above $700^{\circ}C$. Dielectric constants and dielectric losses of the PZT films were 900~1200and 2~5%, respectively. Piezoelectric constant $d_{33}$ of the PZT films constrained by a substrate were 200pm/V at 100kV/cm.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2271-2278
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• 2007

Electron transfer of a redox protein at a bare gold electrode is too slow to observe the redox peaks. A novel Nafion-riboflavin functional membrane was constructed during this study and electron transfer of cytochrome c, superoxide dismutase, and hemoglobin were carried out on the functional membrane-modified gold electrode with good stability and repeatability. The immobilized protein-modified electrodes showed quasireversible electrochemical redox behaviors with formal potentials of 0.150, 0.175, and 0.202 V versus Ag/AgCl for the cytochrome c, superoxide dismutase and hemoglobin, respectively. Whole experiment was carried out in the 50 mM MOPS buffer solution with pH 6.0 at 25 oC. For the immobilized protein, the cathodic transfer coefficients were 0.67, 0.68 and 0.67 and electron transfer-rate constants were evaluated to be 2.25, 2.23 and 2.5 s?1, respectively. Hydrogen peroxide concentration was measured by the peroxidase activity of hemoglobin and our experiment revealed that the enzyme was fully functional while immobilized on the Nafion-riboflavin membrane.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.10
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• pp.34-43
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• 1990

An improved parameter adaptation and control law for robot manipulator are proposed based on a linearized parametric system equation and augmented error vectors. In view of the modeling error and parasitics with small time constants which inevitably introduced during modelling process, their effects on the robustness of the system performance are reviewed and as an conutermearsure, adaptation mechanism with low pass filter is proposed. Proposed parameter adaptation and control low assure the stability of the robot manipulator in the large without further assumption. Computer simulation shows its effectiveness of the proposed adaptation mechanism to improve the robustness of the system in presence of the parasitics in the system and superior performance for high speed operations make it an attractive option in application of the adaptive control field for robot manipulator.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.35-38
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• 2005

The Objective of this work was to design Composite Antenna Structures (CAS) and investigate impact behavior of CAS which was various curvature. This term, CAS, indicates that structural surface becomes antenna. Constituent materials were selected considering electrical properties, dielectric constants and tangent loss as well as mechanical properties. For the antenna performance, microstrip antenna layers inserted into structural layers were designed for satellite communication at the resonant frequency of 12.5 GHz and final demonstration article was. After making five kinds of curved CAS, which radii of curvature are flat, 200, 150, 100, 50 mm. The antenna performance changed in accordance with variation of curvature. The Reflection coefficient was independent of curvature but the gain decreased with the radius of curvature. The impact test equipment was Dyna-8250 drop weight tester. The impact characteristic in accordance with curvature is maximum absorb energy is same each other. The impact energy was 8.5 J. For various Impact energy test, five energy levels 3 J, 5 J, 7 J, 10 J, 20 J were used. The performance of impact damaged antenna was estimated by measuring the return loss and the radiation pattern. It was revealed that the performance of antenna was not related to the impact damage. Because the impactor did not damage the patch directly. CAS have good impact stability for the antenna performance.