• Journal of the Korean Ceramic Society
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• v.27 no.2
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• pp.187-194
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• 1990

Effects of MnO2 addition ranged from 0.0wt% to 5.0wt% on the microstructure and dielectric and piezoelectric properties of the Pb(Zr0.52 Ti0.48)O3 Ceramics have been investigated. The solubility limit of MnO2 in Pb(Zr0.52 Ti0.48)O3 is about 0.5wt%, and MnO2 as a valence state of Mn3+ is substituted for (Zr, Ti) lattice site in PZT solid-solution. The addition of MnO2 up to 0.5wt% in Pb(Zr0.52 Ti0.48)O3 brings increase of density, but decreased of grain size and tetragonality. Dielectric constant slightly decreases, but both coupling factor(Kp) and mechanical quality factor(Qm) increase with the addition of MnO2. However, excess amount of MnO2 addition more than 0.75wt% results in rapid decrease of resistance. Dielectric constant and tan $\delta$ increase due to the second phase and inhomogeneous Mn distribution.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.378.2-378.2
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• 2014

We have investigated optical characteristics of $p-Ge_{0.99}Sn_{0.01}$ and Ge films grown on Si substrates using photoreflectance (PR) spectroscopy. The $Ge_{0.99}Sn_{0.01}$ and Ge films were grown by using an ultra-high vacuum chemical vapor deposition and molecular beam epitaxy methods, respectively. PR spectra were measured at 25 K and an extended InGaAs detector was used. By comparing $Ge_{0.99}Sn_{0.01}/Si$ and Ge/Si spectra, we observed the signals related to direct transition and split-off band of $Ge_{0.99}Sn_{0.01}$. The transition energies of $Ge_{0.99}Sn_{0.01}$ and Ge films were approximately 0.74 and 0.84 eV, respectively. Considering the shift of split-off band transition of $Ge_{0.99}Sn_{0.01}$, we suppose that the transition at 0.74 eV is attributed to direct transition between ${\Gamma}$ band and valence band. The temperature- and excitation power-dependent PR spectra were also measured.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.198-203
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• 2014

In this study, steam reforming reaction and surface characteristics of Ni metal foam plate were investigated. Valence state of Ni could be changed by pretreatment, and metallic Ni species exposed on surface as a active site play important role in steam reforming reaction. Porous catalytic membrane also was prepared by mixing of Ni metal foam plate and Ni-YSZ catalyst to control the pore size and assign the catalytic function in Ni metal foam plate. In SEM analysis results, Pore size of Ni metal foam plate could be controlled and Ni-YSZ catalyst well dispersed on surface. Ni based porous catalytic membrane had a similar steam reforming activity regardless of space velocity.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.04a
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• pp.44-56
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• 1998

Effects of the music and white noise on recovery of the autonomic and cortical responses evoked by aversive visual stimulation were analyzed in 20 subjects. It was suggested that the music is able to exert modulatory influence on the physiological activity resulted from exposure to unpleasant IAPS based stimuli. Spectral power of DDG, heart rate(HR)respiration rate (RSR) and electrodermal activity(EDA)were recorded and analyzed for each experimental condition. It was observed HR and RSR deceleration, increased EDA and electrocortical activation expressed in decreased alpha power and increase of delta activity ao occipital and frontal areas. Obtained results suggest that audutory stimulation both with pleasant and sad music lead to restoration of pre-stimulation activation levels of most physiological parameters during listenning to music and in post-stimulation period. White noise evoked short-term physiological responses typical for orienting reaction and quite distinct from changes produced by music. Available data to differentiate effeces among pleasant and sad music, due toqualitative similarities of physilolgical patterns, but suppert an assumption that music is capable to facilitate the process of recovery of physilolgical responses elicited by visual stimulation of negative valence, thus positively modulate post-stress state.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1341-1345
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• 2007

The surface chemistry of D2O dosed Zircaloy-4 (Zry-4) surface followed by Ar-ion bombardment and annealing was studied by means of X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS). In the XPS study, Ar-ion bombardment caused decrease of the oxygen on the surface region of Zry-4 and therefore led to change the oxidation states of the zirconium from oxide to metallic form. In addition, oxidation states of zirconium were changed to lower oxidation states of zirconium due to depopulation of oxygen on the surface region by annealing. Up to about 787 K, the bulk oxygen diffused out to the subsurface region and after this temperature, the oxygen on the surface of Zry-4 was depopulated. UPS study showed that the valence band spectrum of the D2O exposed Zry-4 exhibited a dominant peak at around 13 eV and no clear Fermi edge was detected. After stepwise Ar+ sputtering processes, the decrease of the oxygen on the surface of Zry-4 led to suppress the dominant peak around 13 eV, the peak around 9 eV and develop a new peak of the metallic Zr 4d state (20.5-21.0 eV) at the Fermi level.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.593-599
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• 1990

A series of new, square planar, and mixed-ligand complexes of Ni(Ⅱ), Pd(Ⅱ), and Pt(Ⅱ) have been prepared. From the observation of electronic spectrum for the variation of the ligand substituents, the very intense absorption band in the visible range is by the electronic transition of dithiolene to diimine ligand, HOMO to LUMO. In the various solvent systems the IT band shows the similar behavior to IT transition of mixed-valence dinuclear complexes followed with Hush theory, happens rto dominently by the inner sphere charge transfer transition. The negative solvatochromism represents that the excited-state electric dipole is reduced or reversed by the electronic transition.

• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1341-1348
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• 2009

Electrocatalytic oxidation of two anti-inflammatory drugs (Mefenamic acid and Indomethacin) was investigated on a cobalt hydroxide modified glassy carbon (CHM-GC) electrode in alkaline solution. The process of oxidation and its kinetics were established by using cyclic voltammetry and chronoamperometry techniques as well as steady state polarization measurements. Voltammetric studies indicated that in the presence of under study drugs, the anodic peak current of low-valence cobalt species increased, followed by a decrease in the corresponding cathodic current. This result indicates that the drugs were oxidized via cobalt hydroxide species immobilized on the electrode surface via an E$\acute{C}$ mechanism. A mechanism based on the electrochemical generation of Co (IV) active sites and their subsequent consumption by the drugs in question was also investigated. The constants rate of the catalytic oxidation of the drugs and the electron-transfer coefficients reported.

• Journal of the HCI Society of Korea
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• v.5 no.1
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• pp.11-18
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• 2010

Cell phone users frequently send and receive text messages with emoticons in their everyday lives, but emoticon and its emotional effect on message in mobile context has not been focused on. The purpose of this study is to investigate the emotional effect of emoticons on interpretation of text message considering valent texts and emoticons. Study 1 showed the effect of valent emoticons on neutral message, and also revealed that existence of emoticon, regardless of its valence, decreases rigidness and increases familiarity of message. In Study 2 that used positive and negative text messages, we found that emoticon still affects assessing sender's mood state and emotion. Result of interaction between valences of text and emoticon showed that participants in condition of incongruent pairs felt more sarcasm.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1305-1306
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• 2006

A monolayer assembly of anthracene-viologen linked thiol ($AMVC_{8}SH$) was fabricated on a gold electrode by self-assembly method. Structural property of the self-assembled monolayers (SAMs) was carried out by optical and electrochemical method. Firstly, we investigated PL spectrum and UV/visible absorption for the optical properties in solution state. Secondly, we determined the characteristics of charge transfer in different electrolyte solutions by electrochemical quartz crystal microbalance (EQCM). From the data, the PL spectrum and UV/visible absorption were observed and the well-defined shape peaks were nearly equal charges during redox reactions and existed to an excellent linear relationship between the scan rates and existed to currents. The mass change was determined during redox reaction. The mass change behavior of SAMs was not only governed by the mobility of the ion in the viologen but the valence of the ion in the electrolyte solution.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.35-35
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• 2010

Understanding the mechanistic details of heterogeneous catalytic reactions will provide a way to tune the selectivity between various competing reaction channels. In this regard, catalytic decomposition of alcohols over the rutile $TiO_2$(110) surface as a model oxide catalyst has been studied to understand the reaction mechanism employing the temperature-programmed desorption (TPD) technique. The $TiO_2$(110) model catalyst is found to be active toward alcohol dehydration. We find that the active sites are bridge-bonded oxygen vacancies where RO-H heterolytically dissociates and binds to the vacancy to produce alkoxy (RO-) and hydroxyl (HO-). Two protons adsorbed onto the bridge-bonded oxygen atoms (-OH) readily react with each other to form a water molecule at ~500 K and desorb from the surface. The alkoxy (RO-) undergoes decomposition at higher temperatures into the corresponding alkene. Here, the overall desorption kinetics is limited by a first-order decomposition of intermediate alkoxy (RO-) species bound to the vacancy. We show that detailed analysis on the yield and the desorption temperatures as a function of the alkyl substituents provides valuable insights into the reaction mechanism. After the catalytic role of the oxygen vacancies has been established, we employed x-ray photoelectron spectroscopy to further study the surface electronic structure related to the catalytically active defective sites. The defect-related state in valence band has been related to the chemically reduced $Ti^{3+}$ defects near the surface region and are found to be closely related to the catalytic activity of the $TiO_2$(110) surface.