• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.134-139
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• 1998

Amorphous fluorocarbon (a-C:F) is of interest for low dielectric interlayer material, but in this work we applied this material to FED field emitter. N-doped a-C:F films were deposited by inductively coupled plasma chemical vapor deposition (ICPCVD). The Raman spectra were measured to study the film structure and inter-band optical absorption coefficients were measured using Perkin-Elmer UV-VIS-IR spectrophotometer and optical band gap was obtained using Tauc's plot. XPS spectrum and AFM image were investigated to study bond structure and surface morphology. Current-electric field(I-E) characteristic of the film was measured for the characterization of electron emission properties. The optimum doping concentration was found to be [N2]/[CF4]=9% in the gas phase. The turn-on field and the emission current density at $[N_2]/[CF_4]$=9% were found to be 7.34V/$\mu\textrm{m}$ and 16 $\mu\textrm{A}/\textrm{cm}^2$ at 12.8V/$\mu\textrm{m}$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.139-140
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• 2005

The photocurrent characteristics of CdTe/HgTe/CdTe structured nanoparticles are studied. CdTe/HgTe/CdTe multilayer structured nanoparticles were synthesized by colloidal method. CdTe/HgTe/CdTe multilayer structured nanoparticles were characterized by x-ray diffraction, high-resolution transmission electron microscopy(HRTEM), absorbance and photoluminescence(PL). PL spectrum of CdTe/HgTe/CdTe multilayer structured nanoparticles exhibits a strong exciton bond in the near infrared range. The I-V curves and photoresponses revealed that CdTe/HgTe/CdTe multilayer structured nanoparticles are very prospective materials for the photodetectors.

• Bulletin of the Korean Chemical Society
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• v.20 no.10
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• pp.1149-1152
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• 1999

1H NMR spectrum of a DMF-d7 solution containing 4-aminopyrimidine and [SiW11CoIIO39]6- (SiW11Co) shows separate peaks from two linkage isomers, a and b, in which N(1) and N(3) of the pyrimidine ring are coordinated to SiW11Co, respectively. The signal from the amine group in the isomer a exhibits temperature dependence that is characteristic of a two-site exchange problem. Rates of internal rotation of the amine group were determined by simulating the NMR spectra at 5-35℃. The amine group of free 4-aminopyrimidine also shows temperature-dependent spectra at lower temperatures; rates of internal rotation at (-25)-25℃ were determined. The internal rotation of the amine group in the complex is much slower than that for free 4-aminopyrimidine, indicating that π-character of the C-N bond increases on coordination to SiW11Co. The amine group in the isomer b does not show such behavior. It is probable that hydrogen bonding between N-H and a bridging oxygen atom of SiW11Co prevents it from rotating at low temperatures.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.149-155
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• 1989

1H-nmr chemical shifts and lineshapes of amino-protons of thioacetamide in n-alcohols were determined. The chemical shifts are discussed by the Reichardt's solvent polarity parameter, $E_T(30)$. The following relationship between ${delta}_{obs}\;and\;E_T(30)$ was obtained, ${\delta}_{obs}=a{\cdot}E_T(30)＋b{\cdot}(E_T(30))_2$ where a is a characteristic constant for the protons of thioacetamide in n-alcohol solutions and b is a constant for the solute(TA)-solvent (n-alcohols) interactions. The barrier of the hindered rotation about the N-C(S) bond in TA was obtained by analysis of the lineshape of the amino-protons in TA. The behavior of the hindered rotation as well as chemical shifts of the amino-protons in TA has been found to be closely related to the $E_T(30)$ of n-alcohols.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2711-2719
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• 2013

Hydrogen bonding interaction between alcohols and water molecules is an important characteristic in the aqueous solutions of alcohols. In this paper, a series of molecular dynamics simulations have been performed to investigate the aqueous solutions of low molecular weight alcohols (methanol, ethylene glycol and glycerol) at the concentrations covering a broad range from 1 to 90 mol %. The work focuses on studying the effect of the alcohols molecules on the hydrogen bonding of water molecules in binary mixtures. By analyzing the hydrogen bonding ability of the hydroxyl (-OH) groups for the three alcohols, it is found that the hydroxyl group of methanol prefers to form more hydrogen bonds than that of ethylene glycol and glycerol due to the intra-and intermolecular effects. It is also shown that concentration has significant effect on the ability of alcohol molecule to hydrogen bond water molecules. Understanding the hydrogen bonding characteristics of the aqueous solutions is helpful to reveal the cryoprotective mechanisms of methanol, ethylene glycol and glycerol in aqueous solutions.

• Journal of Korean Association for Spatial Structures
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• v.5 no.4 s.18
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• pp.71-77
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• 2005

Bonded CFRP Plate method used murk in reinforcement method is very efficient for stress increment of reinforced members. But CFRP plate dosen't display enough its capacity and have the destruction characteristic of premature failure that reach failure by debond plate, because near-surface-bond using epoxy. Such destruction character of reinforced specimens take the influence at variables as steel reinforcement ratio, concrete strength, kind of reinforcement materials, reinforced length, property of epoxy used in binder and so on. In this study, performed experiment results are compared and considered on flexural performance of Near Surface Mounted Reinforcement used CFRP-Rod, as complement about structural behavior of RC beam reinforced flexural capacity in CFRP plate and premature failure of reinforcement material. Main variables of RC beam applied CFRP Plate external bond method are experimental variables as reinforcement length, reinforcement position (tension face and side face of beam) and existence of ironware in end parts. In case of CFRP-Rod, variable is reinforcement length.

• Analytical Science and Technology
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• v.8 no.2
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• pp.139-159
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• 1995

Positive ion mass spectra of some corticosteroids were obtained by using liquid chromatography-mass spectrometry(LC-MS). The base peak of each compound showed the protonated molecular ion [$MH^+$], ammonium adduct ion [${MNH_4}^+$] or [$MH^+-60$] ion according to its chemical structure and other characteristic mass ions were [$MH^+-18$], [${MNH_4}^+-18$] and so on. Several rat urinary metabolites of methylprednisolone acetate after the oral administration were detected by the thermospray LC-MS. The identified major metabolites were 20-hydroxymethylprednisolone(20-HMP), methylprednisolone(MP) and methylprednisone(11-KMP), which were supposed to be formed by deacetylation at the position of C-21, reduction at C-20, oxidation at C-11, or due to the bond cleavage between C-17 and C-20.

• Journal of the Korean Vacuum Society
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• v.8 no.1
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• pp.63-69
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• 1999

The characteristic parameters of high density plasma source (Helical Resonator) have been measured with Langmuir probe to get the plasma density electron temperature, ion current density, etc. Optical emission spectra of Si and SiCl have been analyzed in $Cl_2$$/poly-Si system to elucidate etching mechanism. In this system, the main reaction to remove silicon atoms on the surface is proceeding mostly through chemical reaction, not pure physical reaction. The emission intensity of SiCl (chemical etching product) increases much faster than Si (pure physical etching product) with increasing the concentration of impurities (P). This is due to the electron transfer from substrate to the surface via Si-Cl bond. As a result, Si-Cl bond becomes more ionic and mobile, therefore the Cl-containing etchant forms $SiCl_x$ with surface more easily. Consequently, for the removal of Si atom from poly silicon surface, the chemical etching is more favorable than physical etching with increasing P concentrations.

• Journal of Welding and Joining
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• v.25 no.5
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• pp.45-50
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• 2007

The Ni-base superalloy GTD111 DS is used in the first stage blade of high power land-based gas turbines. Advanced repair technologies of the blade have been introduced to the gas turbine industry over recent years. The effect of the filler metal powder on Transient Liquid Phase bonding phenomenon and tensile mechanical properties was investigated on the GTD111 DS superalloy. At the filler metal powder N series, the base metal powders fully melted at the initial time and a large amount of the base metal near the bonded interlayer was dissolved by liquid inter metal. Liquid filler metal powder was eliminated by isothermal solidification which was controlled by the diffusion of B into the base metal. The solids in the bonded interlayer grew from the base metal near the bonded interlayer inward the insert metal during the isothermal solidification. The bond strength of N series filler metal powder was over 1000 MPa. and ${\gamma}'$ phase size of N series TLP bonded region was similar with base metal by influence of Ti, Al elements. At the insert metal powder M series, the Si element fluidity of the filler metal was good but microstructure irregularity on bonded region because of excessive Si element. Nuclear of solids formed not only from the base metal near the bonded interlayer but also from the remained filler metal powder in the bonded interlayer. When the isothermal solidification was finished, the content of the elements in the boned interlayer was approximately equal to that of the base metal. But boride and silicide formed in the base metal near the bonded interlayer. And these boride decreased with the increasing of holding time. The bond strength of M series filler metal powder was about 400 MPa.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.509-516
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• 1990

1H-nmr chemical shifts and lineshapes of amino-protons of acetamide (AA) in n-alcohols were determined. The chemical shifts are discussed by the Reichardt's solvent polarity parameter, E$_{T}$(30). The following relationship between $\delta$obs and E$_{T}$(30) was obtained. ${\delta}_{obs}$ = ${\delta}_{o}$ ＋ aE$_{T}$ (30) ＋ b[E$_{T}$(30)]$^2$ where ${\delta}_{o}$ is the chemical shift of the solute in gaseous state or at $E_{T}$(30) = 0, a is a characteristic constant for the protons of AA in n-alcohol solutions and b is a constant for the solute (AA)-solvent (n-alcohols) interaction. The barrier of the hindered rotation about the N-C(O) bond in AA was obtained by analysis of the lineshapes of the amino-protons in AA. The behavior of the internal rotation as well as chemical shifts of the amino-protons in AA has been found to be closely related to the $E_{T}$(30) of n-alcohols.