• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.731-733
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• 1998

PID controllers are widely used in the process industries such as power plants and chemical plants. Several methods for determining PID controller parameters have been suggested to improve tuning results by various performance criteria during the past years. These methods may not produces satisfactory closed loop response by the characteristics of controlled processes. In this paper, using a model of gas turbine system obtained by operating data of Gunsan C/C, we examines the performance of PI controllers determined by various performance criteria and suggests which tuning methods can be optimally used in gas turbine control system of Gunsan C/C.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.228-229
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• 2001

Electroluminescent polymers have attracted considerable attention due to possible applications as large-area light-emitting displays. There have been many efforts to improve the electroluminescent efficiency. To design the polymer with high efficiency, it is necessary to understand the luminescent mechanism. In this report, we have investigated two-photon absorption(2PA) characteristics of highly efficient electroluminescent polymer using various techniques such as nonlinear transmission, 2PA-induced photoluminescence(2PA-PL) and 2PA-induced photoconductivity(2PA-PC). (omitted)

• Journal of Integrative Natural Science
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• v.3 no.1
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• pp.24-27
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• 2010

Multi-functionalized rugate porous silicon (PSi) for biosensor was developed by hydrosilylation with silole and its further reaction with biotin groups. PSi was generated by an electrochemical etching of silicon wafer in aqueous ethanolic HF solution PSi prepared by using etching conditions showed that many sharp spectral lines can be obtained in the optical reflectivity spectrum. 1,1-hydrovinyl-2,3,4,5-tetraphenylsilole was obtained from the reaction of 1,1-dilithio-2,3,4,5-tetraphenyl-1,3-butadiene with dichlorovinylsilane. Multi-functionalized PSi with silole and biotin groups was characterized by UV-vis absorption spectroscopy, Ocean optics 2000 spectrometer, and fluorescence spectroscopy. Optical characteristics such as reflectivity and photoluminescence (PL) were observed. An increase of the reflection wavelength in the reflectivity spectrum by 20 nm was observed, indicative of a change in refractive indices induced by hydrosilylation of the silole and biotin groups to the rugate PSi. This red-shift was attributed to the replacement of some of the Si-H group of fresh rugate PSi with silole and biotin group.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.52.1-52.1
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• 2016

We introduce the characteristics and performance of the 0.25m telescope at Mangpo high school Unmanned Robotic Observatory (MURO) which was established in Yangpyeong-gun, Gyeongi-do, KOREA in 2015 January. MURO system included Astrohaven 2.1m non-rotation fiberglass clamshell dome, Paramount MEII mount, Takahashi CCA 0.25m wide field telescope, FLI PL 16803 4K CCD with 7-positions filter wheel system, all sky camera and point grey wide field camera, IR 4 chanel heat sensor camera for security, DAVIS realtime weather cast, and power controled by ARS system. All control softwares are from off-the-shelf products based on Windows 7 OS to be easily operated and maintained. We expect to perform variety of science programs ranging from supernovae follow-up observation to narrow band imaging survey as well as science class activities at Mangpo high school.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.2
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• pp.71-75
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• 2014

To observe the optical characteristic of oxide semiconductor depending on the degree of bonding structures, SiOC, ZnO and IGZO were prepared by the RF magnetron sputter system and chemical vapor deposition. Generally, crystal ZnO, amorphous SiOC and IGZO changed the optical characteristics in according to the electro-chemical behavior due to the oxygen vacancy at an interface between different groups. Transmittance of SiOC and IGZO with amorphous structures was higher than that of ZnO with crystal structure, because of lowering the carrier concentration due to the recombination of electron and holes carriers as oxygen vacancies. Besides, the energy gap of amorphous SiOC and IGZO was higher than the energy gap of crystal ZnO. The diffusion mobility of holes is higher than the drift mobility of electrons.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1402-1404
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• 2009

The silicon nitride films for gate dielectric were deposited by catalytic chemical vapor deposition at low temperature (${\leq}200^{\circ}C$). The mixture of $SiH_4$, $NH_3$ and $H_2$ was used as source gases. The current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of the films were measured. The breakdown voltage and the flat band voltage shift of samples were improved by increase of the $NH_3$ contents and $H_2$ dilution ratio. The defect states were analyzed by photoluminescence (PL) spectra. As the defect states decreased, the breakdown voltage and the flat band voltage shift increased.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.6
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• pp.241-245
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• 2003

ZnO thin films on (l00) p-type Si and sapphire substrates have been deposited by a pulsed laser deposition technique using an Nd:YAG laser with a wavelength of 266 nm. The influence of the deposition parameters such as oxygen pressure, substrate temperature and laser energy density on the properties of the grown films was studied. The experiments were performed for substrate temperatures in the range of 200∼50$0^{\circ}C$ and oxygen pressure in the range of 100∼700 sccm. All of the films grown in this experiment show strong c-axis orientation with (002) textured ZnO peak. With increasing substrate temperature, the FWHM (full width at half maximum) and surface roughness were decreased. In the case of using sapphire substrate, the intensity of PL spectra increased with increasing ambient oxygen flow rate. We investigated the structural and morphological properties of ZnO thin films using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM).

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.798-802
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• 2010

From time-resolved optical emission spectra, we have investigated the effects of a transverse magnetic field on the expansion of a plasma plume produced by laser ablation of a ZnO:$P_2O_5$ ceramic target in oxygen active atmosphere. The emission spectra of $Zn^{+*}$, $P^{+*}$, and $Zn^*$ neutrals in the presence of magnetic field turn out to be considerably different from those without magnetic field. The characteristics of the deposited films grown on amorphous fused silica substrates by pulsed laser deposition (PLD) are examined by analyzing their photoluminescence (PL), X-ray diffraction (XRD), and UV-visible spectra.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.12a
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• pp.109-116
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• 2003

Amorphous GaN Quantum dots(a-GaN QDs) with particle diameters less than bohr radius(~11nm) were successfully fabricated at room temperature by a laser ablation of high densified GaN target. Transmission electron microscopy, SAED diffraction pattern and X-ray photoelectron spectroscopy confirmed the presence of a-GaN QDs with particle size of 7.9, 6.9, 4.4nm under the Ar gas pressures of 50, 100 and 200 Pa, respectively. The room temperature PL and absorbance spectra showed a strong band emission centered at 3.9 eV in a-GaN QDs made under the gas pressures of 100 and 200 Pa, which is nearly 0.5eV blueshifted with respect to the bulk crystal band gap.

• Journal of the Semiconductor & Display Technology
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• v.14 no.3
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• pp.27-31
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• 2015

It was the electrical properties of ZnS treated by the annealing in a vaccum and an atmosphere conditions to reseached the leakage current effect of semiconductor devices. Most samples were shown the non-linear with unipolar properties, but the ZnS annealed at $100^{\circ}C$ in a vaccum was only observed no leakage current in a range of -20 V< voltage < 15 V. The crystallinity of ZnS with no leakage current was improved and optical property was also improved. Because the ambipolar characteristics and low leakage currents originated from the extension effect of a depletion width by electron-hole combination in the depletion layer.