• Communications of the Korean Mathematical Society
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• v.19 no.2
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• pp.293-305
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• 2004

Trotter-Kato type approximations of the convoluted solution operator families for the Volterra integral equations (V $E_n$): v(t)=$A_{n} \int_0^t v(t-s) d\mu_n(s) + f_n(t), t \geq 0$ and the convergence of the solutions to the equations (V $E_n$) are studied.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.4
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• pp.51-58
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• 1985

A simple model for the impurity profile in an ion-implanted channel layer of an enhance-ment type IGFET is assumed and a simple expression for the threshold voltage is derived by the assumed impurity profile. In application, the concept of correction factor K is used and the value of threshold voltage is well agreed with experimental value. Also, 1-V character-istics curve is well agreed with experimental value. In addition, this program is packaged and is utilized.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.916-922
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• 1997

A superconducting phase La2CuO4+δ (Tc=44 K) has been prepared by electrochemical oxidation which allows the oxygen to intercalat into the La2O2 layers. According to the Cu K-edge X-ray absorption near edge structure spectroscopic analysis, the oxidized phase shows an overall spectra shift of about 0.5 eV to a higher energy region compared to the as sintered one with the occurrence of an additional peak corresponding to the transition to the |1s13dn+1L-14pσ1 > final state, indicating the oxidation of CuO2 layer. From the X-ray photoelectron spectroscopic studies, it is found that the binding energy of La 3d5/2 is significantly shifted from 834.3 eV (as sintered La2CuO4) to 833.6 eV (as electrochemically oxidized La2CuO4+δ), implying that the covalency of the (La-O) bond is decreased due to the oxygen intercalation. The O 1s spectra do not provide an evidence of the superoxide or peroxide, but the oxide (O2-) with the contaminated carbonate (CO32-) based on the peaks at 529 eV and 532 eV, respectively, which is clearly confirmed by the Auger spectroscopic analysis. Oxygen contents determined by iodometric titration (δ=0.07) and thermogravimetry (δ=0.09) show good coincidence each other, also giving an evidence for the "O2-" nature of excess oxygen. From the above results, it is concluded that "O2-" appeared as O 1s peak at 528.6 eV is responsible for superconductivity of La2CuO4+δ.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.105-110
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• 2003

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively, the defects of the epilayer were investigated by means of the low-temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, $I_{2}$ ($D^{\circ}$, X), bounded to the neutral donor associated with the Se-vacancy. This donor-impurity binding energy was calculated to be 25.3 meV, The exciton peak, $I_{1}^{d}$ at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy. The $I_{1}^{d}$ peak was dominantly observed in the ZnSe/GaAs : Se epilayer treated in the Se-atmosphere. This Se-atmosphere treatment may convert the ZnSe/GaAs : Se epilayer into the p-type. The SA peak was found to be related to a complex donor like a $(V_{se}-V_{zn})-V_{zn}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.365-370
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• 2000

Schottky contacts on n-In$\_$0.53//Ga$\_$0.47//As have been made by metal deposition on substrates cooled to a temperature of 77K. The current-voltage and capacitance-voltage characteristics showed that the Schottky diodes formed at low temperature had a much improved barrier height compared to those formed at room temperature. The Schottky barrier height ø$\_$B/ was found to be increased from 0.2eV to 0.6eV with Ag metal. The saturation current density of the low temperature diode was about 4 orders smaller than for the room temperature diode. A current transport mechanism dominated by thermionic emission over the barrier for the low temperature diode was found from current-voltage-temperature measurement. Deep level transient spectroscopy studies exhibited a bulk electron trap at E$\_$c/-0.23eV. The low temperature process appears to reduce metal induced surface damage and may form an MIS (metal-insulator-semiconductor)-like structure at the interface.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.82-82
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• 2003

p-CdI $n_2$T $e_4$ 단결정을 Bridgeman법으로 3단 수직 전기로에서 성장하였다. 성장된 결정의 결정성은 X선 회절과 광발광 측정으로 조사하였다 막 성장된(as-grown) 결정과 여러 열처리 CdI $n_2$T $e_4$ 결정들의 광발광 스펙트럼 측정으로부터 CdI $n_2$T $e_4$:Cd 광발광에서는 중성 주개 bound 엑시톤 ( $D^{\circ}$,X)가 우세함을 발견하였고 반면에 CdI $n_2$T $e_4$:Cd 광발광에서는 중성 받개 bound 엑시톤 ( $A^{\circ}$,X)가 완전히 사라졌다. 더우기, CdI $n_2$T $e_4$:Te의 광발광 스펙트럼에서 중성 받개 bound 엑시톤 ( $A^{\circ}$,X) 발광은 막 성장된 CdI $n_2$T $e_4$결정에서처럼 우세하였다. 이러한 결과들은 ( $D^{\circ}$,X)가 주개로써 작용하는 $V_{Te}$ ,와 관련이 있고, ( $A^{\circ}$,X)는 받개로 작용하는 $V_{cd}$와 관련이 있음을 가리킨다. p-CdI $n_2$T $e_4$ 결정은 Cd 증기 분위기에서 열처리한 후에는 n형으로 type conversion이 된다는 것을 알았다. 중성 주개-받개 bound 엑시톤 ( $D^{\circ}$, $A^{\circ}$)과 이들의 TO 포논 복제의 발광은 $V_{Te}$ 나 C $d_{int}$와 같은 주개들과 $V_{cd}$ 또는 T $e_{int}$와 같은 받개들 사이의 상호 작용과 관련이 있다. 또한, CdI $n_2$T $e_4$에서 In은 안정된 결합의 형태로 있기 때문에 자연 결함의 형성에는 관련이 없음을 알았다 알았다았다았다

• Journal of fish pathology
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• v.32 no.2
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• pp.97-104
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• 2019

The purpose of this study was to investigate the antimicrobial resistance and resistance transfer of Vibrio parahaemolyticus and Morganella morganii isolated from fish products purchased from fish markets in Yeosu April - December 2017. These bacteria were identified by biochemical test and PCR results, and the transfer of antimicrobial resistance was confirmed by the broth mating method. To isolate the transconjugants formed during conjugation, TSA medium containing 50 ㎍/ml of ampicillin (AMP), and 150 ㎍/ml of streptomycin (SM) or 30 ㎍/ml of oxytetracycline (OT) was used. M. morganii isolates showed low susceptibility to AMP, amoxicillin (AML), and colistin (CT), erythromycin, OT, and tetracycline, compared to V. parahaemolyticus resistance to AMP, AML, and CT. The conjugation of V. parahaemolyticus or M. morganii with Escherichia coli resulted in the separation of V. parahaemolyticus and M. morganii showing SM resistance as transconjugants. Meanwhile, Edwardsiella tarda transconjugants showing AMP and AML resistance were obtained from the broth mating of V. parahaemolyticus and E. tarda. But the transfer of the VPA0477 which is a β-lactamase gene of V. parahaemolyticus was not confirmed. These results suggest that resistance transfer between pathogenic bacteria is bidirectional and progresses in a wide variety of patterns.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.230-233
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• 2004

The stochiometric mix of evaporating materials for the $CuInS_2$ single crystal thin films was prepared from horizontal furnance. Using extrapolation method of X-ray diffraction patterns for the $CuInS_2$ polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.524\;{\AA}$ and $11.142\;{\AA}$, respectively. To obtain the single crystal thin films, $CuInS_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperature were 640 t and 430 t, respectively and the thickness of the single crystal thin films was $2{\mu}m$. Hall effect on this sample was measured by the method of van dot Pauw and studied on carrier density and temperature dependence of mobility. The carrier density and mobility deduced from Hall data are $9.64{\times}10^{22}/m^3,\;2.95{\times}10^{-2}\;m^2/V{\cdot}s$ at 293 K, respectively The optical energy gaps were found to be 1.53 eV at room temperature. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the thin film, we have found that the values of spin orbit coupling splitting ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 0.0211 eV and 0.0045 eV at 10 K, respectively. From PL peaks measured at 10K, 807.7nm (1.5350ev) mean Ex peak of the free exciton emission, also 810.3nm (1.5301eV) expresses $I_2$ peak of donor-bound exciton emission and 815.6nm (1.5201eV) emerges $I_1$ peak of acceptor-bound exciton emission. In addition, the peak observed at 862.0nm (1.4383eV) was analyzed to be PL peak due to donor-acceptor pair(DAP).

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1645-1647
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• 2004

Potential energy surfaces for the reaction Al + $O_2{\to}$AlO + O have been calculated with the multireference configuration interaction (MRCI) method using molecular orbitals derived from the complete active space selfconsistent field (CASSCF) calculations. The end-on geometry is the most favourable for the reaction to take place. The small reaction barrier in the present calculation (0.11 eV) is probably an artefact related to the ionicneutral avoided crossing. The charge analysis implies that the title oxidation reaction occurs through a harpooning mechanism. Along the potential energy surface of the reaction, there are two stable intermediates of $AlO_2(C_{{\infty}v}$ and $C_{2v}$) at least 2.74 eV below the energy of reactants. The calculated enthalpy of the reaction (-0.07 eV) is in excellent agreement with the experimental value (-0.155 eV) in part due to the fortuitous cancellation of errors in AlO and $O_2$ calculations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.435-440
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• 2002

In this study, we have investigated photo-induced changes of optical energy gap( $E_{OP)}$ and photoluminescence (PL) in amorphous ($\alpha$-) S $e_{100-x}$G $e_{x}$ (x=5, 25 and 33) thin films prepared by conventional thermal evaporation method. In the $\alpha$-S $e_{100-x}$G $e_{x}$ thin film, the $E_{OP}$ is obtained by a linear extrapolation of the ($\alpha$hν)$^{\frac{1}{2}}$ versus hν plot to the energy axis using the optical absorption coefficient ($\alpha$) calculated from the extinction coefficient k measured in the wavelength range of 290~900nm. Although the values of $\Delta$ $E_{OP}$ are very different, all films exhibit photo-induced photo-darkening (PD) effect that is a red shift of $E_{OP}$ . In particular, $\Delta$ $E_{OP}$ in $\alpha$-S $e_{75}$ G $e_{25}$ thin film exhibits the largest value (i, e., $\Delta$ $E^{OP}$ ~40meV for $\alpha$-S $e_{95}$ G $e_{5}$ , $\Delta$ $E_{OP}$ ~200meV for $\alpha$-S $e_{75}$ G $e_{25}$ , $\Delta$ $E_{OP}$ ~130meV for $\alpha$-S $e_{67}$ G $e_{33}$ ). PL spectra in $\alpha$-SeGe by hν$_{HeCd}$ have no-Stokes shift (SS) and show a tendency dependent on both composition and illumination time. We explain the energy-induced phenomena such as the PD and thermal bleaching, the native charged-defect generation and the no-SS PL, etc..the PD and thermal bleaching, the native charged-defect generation and the no-SS PL, etc..tc..