• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.45-50
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• 1995

The excellent c-axis oriented zinc oxide thin films were prepared by the RF magnetron sputtering method on glass substrates. Optimum fabrication conditions of the ZnO films were such that RF power, substrate temperature, and gas pressure of mixture Ar(50%):$O_{2}$(50%) were 150 W, $200^{\circ}C$, and 5 mTorr, respectively. In these conditions, the deposition rate was $310\;{\AA}/min$, and the resistivity of the film was $1{\times}10^6\;{\Omega}{\cdot}cm$. The ZnO film also showed high c-axis orientation and crystalinity according to XRD pattern and SEM photograph. A fabricated interdigital transducer generated 1st mode surface acoustic wave at 46.6 MHz and 2nd mode surface acoustic wave at 52.5 MHz. At the 1st mode, the phase velocity of surface acoustic wave and the electromechanical coupling coefficient were 2795 m/sec and 0.031 %, respectivly. At the 2nd mode, they were 3149 m/sec and 0.019 %. respectivly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.141-144
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• 2001

An accurate cross sections set are necessary for the quantitatively understanding and modeling of plasma phenomena. By using the electron swarm method. we determine an accurate electron cross sections set for objective atoms or molecule at low electron energy range. In previous paper, we calculated the electron transport coefficients in pure $CF_4$ molecular gas by using two-term approximation of the Boltzmann equation. And by using this simulation method. we confirmed erroneous calculated results of transport coefficients for $CF_{4}$ molecule treated in this paper having 'C2v symmetry' as $C_{3}H_{8}$ and $C_{3}F_{8}$ which have large vibrational excitation cross sections which may exceed elastic momentum transfer cross section. Therefore, in this paper, we calculated the electron transport coefficients(W and $ND_L$) in pure $CF_4$ gas by using multi-term approximation of the Boltzmann equation by Robson and Ness which was developed at lames-Cook university, and discussed an application and/or validity of the calculation method by comparing the calculated results by two-term and multi-term approximation code.

• Laser Solutions
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• v.4 no.3
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• pp.30-39
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• 2001

This work was tamed out to apply a laser welding technique in joining between a Zn coated low carbon steel plate(SECC) and a free cutting carbon steel shaft(SUM24L) with or without W coating. Experiments were carried out and analysed by applying the FD(factorial design)method to obtain the optimum Laser welding condition. Optical microscopy, SEM, TEM and XRD analyses were performed in order to observe the microstructures in the fusion zone and the HAZ. Mechanical properties of the welded specimens were examined by microhardness test, tensile test and twist test. There was no flawed Zn in the fusion zone by EDS analysis. This means that during the welding process, Zn gas could be eliminated by appropriate shielding gas flow rate and butt welding gap. Ni coating itself did not influence on the tensile strength and hardness. However, twist bending strength and the weld depth of the Ni-coated free cutting carbon steel were lower as compared with those of the uncoated free cutting carbon steel. It was attributed to a lower absorbance of laser beam to the shin Ni surface. According to the results of the factorial design tests, the twist bending strength of welded specimens was primarily affected by pulse width, laser power, frequency and speed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.141-144
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• 2001

An accurate cross sections set are necessary for the quantitatively understanding and modeling of plasma phenomena. By using the electron swarm method, we determine an accurate electron cross sections set for objective atoms or molecule at low electron energy range. In previous paper, we calculated the electron transport coefficients in pure CF$_4$ molecular gas by using two-term approximation of the Boltzmann equation. And by using this simulation method, we confirmed erroneous calculated results of transport coefficients for CF$_4$ molecule treated in this paper having 'C2v symmetry'as C$_3$H$_{8}$ and C$_3$F$_{8}$ which have large vibrational excitation cross sections which may exceed elastic momentum transfer cross section. Therefore, in this paper, we calculated the electron transport coefficients(W and ND$_{L}$) in pure CF$_4$ gas by using multi-term approximation of the Boltzmann equation by Robson and Ness which was developed at James-Cook university, and discussed an application and/or validity of the calculation method by comparing the calculated results by two-term and multi-term approximation code.e.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.79-84
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• 2002

An accurate cross sections set is necessary for the quantitatively understanding and modeling of plasma phenomena. By using the electron swarm method, we determine an accurate electron cross sections set for objective atoms or molecule at low electron energy range. It is general calculation that used in this method to an two-term approximation of Boltzmann equation. But it may give erroneous transport coefficients for CF$_4$ molecule treated in this paper having \`C2v symmetry\`, therefore, multi-term approximation of the Boltzmann equation analysis which can consider anisotropic scattering exactly is carried out. It is necessary to require understanding of the fundamental principle of analysis method. Therefore, in this paper, we compared the electron transport coefficients(W and ND$\_$L/) in pure Ar, O$_2$, and CF$_4$ gas calculated by using two-term approximation of the Boltzmann equation analysis code uses the algorithm proposed by Tagashira et al. with those by multi-term approximation by Rubson and Ness which was developed at James-Cook university, and discussed an application and/or validity of the calculation method by comparing these calculated results.

• Korean Journal of Biological Psychiatry
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• v.9 no.1
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• pp.34-41
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• 2002

Background:Since serotonin neurotrasnmission plays an important role in the pathophysiology of depression, the drug that acts on serotonin transporter can be an effective antidepressant. The aim of this study was to investigate the relationship between serotonin transporter polymorphisms(5-HTTLPR) and the long-term effect of the antidepressant treatment. Method:The 175 depressive patients, who met DSM-IV criteria for major depressive disorder or dysthymic disorder were enrolled into three year study. The genotypes of the patients were investigated by polymerase chain reaction of genomic DNA with promoter regions of the serotonin transporter gene. The patients were assessed by the Clinical Global Impression Scale, at the 1st visit, 8th week, 16th week, 1st year, 2nd and 3rd year after the antidepressant treatment. Result:The genotypes of 138 patients were investigated and 128 of them finished this 1st year study and 107 remained in the study after 2-year treatment, and, 97 completed this 3-year study. The therapeutic response of each subset was not different at 8th, 16th week, but the subset with homozygote(l/l) of long variant showed a better antidepressant therapeutic response than heterozygote(l/s). The heterozygote(l/s) showed a better response than the subset with homozygote(s/s) of short variant at 1st, 2nd and 3rd year after the antidepressant treatment in CGI-global improvement score. Conclusion:This result shows that the serotonin transporter polymorphism may be related to the long-term effect of antidepressant treatment and there may be also ethnic difference.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.1059-1065
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• 2003

Antimicrobial activity of Mokdan bark (Paeonia suffruticosa $A_{NDR}$) was investigated. Methanol extract of dried Mokdan was fractionated to hexane, chloroform, ethylacetate, butanol and aqueous fraction. Ethylacetate fraction among these fractions showed the highest inhibitory effect on the microorganisms such as L. monocytogenes, and E. coli at 500 $\mu\textrm{g}$/disc. Ethylacetate fraction was further fractionated into 3 fractions by silica gel column and thin layer chromatography (TLC). The results showed that ethylacetate fractions No. 1 and 2 had the highest antimicrobial activity. They were mixed again, reseparated, and 3 fractions were obtained. Among them, No. 1 had the highest inhibitory effect on the microorganisms, No. 1 fraction was identified as isobutyl isopentanoate by HPLC, and GC-MS.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1041-1046
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• 2011

Micro shockwaves are induced in laser shock peening and their effect on metal samples is presented. Laser shock peening produces maximized internal compressive stress on metal surfaces. This research evaluated the effects of micro shockwaves from laser shock peening with a pulsed Nd:YAG laser on steel samples, through the analysis of the mechanical properties of the samples. In the experiments, a piezo material was applied to measure the micro shockwaves and the hardnesses and micro tensile strengths of the samples were evaluated.

• Journal of Magnetics
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• v.8 no.4
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• pp.142-145
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• 2003

Valence states and electronic structures of Cr-doped $Nd_{1/2}A_{1/2}Mn_{1-y}Cr_{y}O_3$(NAMO; A=Ca, Sr) manganites have been investigated using x-ray absorption spectroscopy (XAS) and high-resolution photoemission spectroscopy (PES). All the Cr-doped NAMO systems exhibit the clear metallic Fermi edges in the Mn $e_{g}$ PES spectra near $E_{F}$. The spectral intensity at $E_{F}$ is higher for Cr-doped N $d_{l}$ 2/S $r_{l}$ 2/Mn $O_3$(NSMO) than for Cr-doped N $d_{l}$ 2/C $a_{l}$ 2/Mn $O_3$ (NCMO), reflecting the stronger metallic nature for NSMO than for NCMO. The measured Cr 2p XAS spectra are found to be very similar to that of C $r_2$ $O_3$, indicating that Cr ions in Cr-doped NAMO are in the trivalent C states ( $t^3$$_{2g}$). The Cr 2p XAS data are consistent with the Cr 3d PES spectra located at ∼1.3 eV below $E_{F}$ and having no emission near $E_{F}$.

• Korean Journal of Optics and Photonics
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• v.16 no.2
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• pp.121-127
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• 2005

This paper presents the thermal characteristics of a Bragg grating recorded in photopolymer. We record hologram gratings using a 532 nm Nd : YAG laser in DuPont HRF 150-38 photopolymer films and analyze the diffraction efficiency versus thermal exposure conditions. For the case of recording after heating, the diffraction efficiency of the hologram is more than $70\%$ at $100^{\circ}C$ but is decreased exponentially at temperatures over $100^{\circ}C$. It is observed in the recording before heating that the diffraction efficiency of the hologram fixed by a UV light is increased to approximately $10\%$ at $100^{\circ}C$, but the holograms are erased at temperatures over $120^{\circ}C$.