• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.64-66
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• 2004

$Pb(Zr_{0.3},Ti_{0.7})O_3$, $Pb(Zr_{0.3},Ti_{0.3})O_3$ powders were prepared by the sol-gel method and PZT heterolayered thick films were fabricated by the screen-printing method. The structural properties as a faction of the composition ration were studied. As a result of the differential thermal analysis (DTA), exothermic peak was observed at around $864^{\circ}C$ dne to the formation of the polycrystalline perovskite phase. The PZT heterolayered thick film sintered at $1050^{\circ}C$ for 10min showed the average grain size $1{\sim}1.4{\mu}m$. The average thickness of PZT heterolayered thick films, obained by $3{\sim}6times$ of screen-printing, was approximately $60{\sim}110{\mu}m$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.313-314
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• 2005

$PbTiO_3$ and PZT(52/48) powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PT/PZT(52/40) heterolayered thick films were fabricated by the screen-printing method on Pt/$Al_2O_3$ substrates. The structural properties such as DTA, X-ray diffraction and microstructure, were examined as a amount of the PbO-$PbF_2$ flux. In the X-ray diffraction analysis, PZT(52/48) thick films showed a perovskite polycrystalline structure without a pyrochlore phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.359-360
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• 2005

PZT(20/80) and PZT(80/20) powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PZT(20/80)/PZT(80/20) heterolayered thick films were fabricated by the screen-printing method on Pt/$Al_2O_3$ substrates. The structural properties such as DTA, X-ray diffraction and microstructure, were examined as a amount of the excess PbO. In the DTA analysis, the formation of the polycrystalline perovskite phase was observed at around $880^{\circ}C$. The average thickness of the PZT heterolayered thick films was approximately $80{\mu}m$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.87-94
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• 2005

A computer code for Electrical Capacitance Tomography (ECT) is developed to sense the cross sectional phase distribution of two-phase flow in the rectangular pipe in which the tomography sensor furnished by the insulated wall, electrodes, and electric field screen. The computer code had two steps for the image reconstruction. In the forward projection step, the sensitivity matrix was constructed based on the electric field calculated by the finite difference method. In the backward projection step, the sensitivity matrix and the measured capacitances were used to reconstruct the cross sectional image. Several algorithms including LBP, TR, ITR, and PLI were employed to find the proper one for the two-phase flow analysis. Since the dielectric constant of the water in two-phase flow is sensitive to the thermal parameter such as, temperature and pressure, the developed code was evaluated to find their accuracy, speed of calculation, and sensitivity to the variation of the dielectric constant. It was found that the iterative methods are superior to the direct methods for the image reconstruction, and the PLI method was the best in the variation of the dielectric constants.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.97-103
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• 2004

In general the starting current of single phase induction motor is 3 to 6times of the rated current It make flickering an electric lamp, dispersion a TV screen, insulation destructing an electric motor and momentary blazing of house wiring. Thus it happens losing an electric power loss and reducing an efficiency and a life of home electrical apparatus. In this paper, we proposed the method of reducing staring current with 3.7(%) using TRIAC and ACCT(alternated current transformer) in order to improve the above problem And also we verified semipermanent system with using semiconductor element.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1274-1284
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• 1999

The Regulatory Guide 1.82 recommends an analysis of hydraulic performance for sump of ECCS (Emergency Core Cooing System) when LOCA(Loss of Coolant Accident) occurs in a nuclear power plant. The present study deals with 3-dimensional, unsteady, turbulent and two-phase flow simulation to examine the behavior of mixture of reactor coolant and debris near the floor of containment building in conjunction with appropriate assumptions. The dispersed solid model has been adjusted to the interfacial momentum transfer between reactor coolant and debris. According to the results, the counterclockwiserecirculation zone had been formed in the region between sump and connection aisle about 376 second after LOCA occurs. The debris thickness accumulated on a sump screen periodically increases or decreases up to 2000 second, afterwards its peak decreases.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.92-92
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• 2012

Chalcopyrite-type Cu(In,Ga)Se2 (CIGS) is one of the most attractive compound semiconductor materials for thin film solar cells. Among various approaches to prepare the CIGS thin film, the powder process offers an extremely simple and materials-efficient method. Here, we present the mechano-chemical synthesis of CIGS compound powders and their use as an ink material for screen-printing. During the synthesis process, milling time and speed were varied in the range of 10~600 min and 100~300 rpm, respectively. Both phase evolution and powder characteristics were carefully monitored by X-ray diffraction (XRD) method, scanning electron microscope (SEM) observation, and particle size analysis by scanning mobility particle spectrometer (SMPS) and aerodynamic particle sizer (APS). We found the optimal milling condition as 200 rpm for 120 min but also found that a monolithic phase of CIGS powders without severe particle aggregation was difficult to be obtained by the mechano-chemical milling alone. Therefore, the optimized milling condition was combined with an adequate heat-treatment (300oC for 60 min) to provide the monolithic CIGS powder of a single phase with affordable particle characteristics for the preparation of CIGS thin film. The powder was used to prepare an ink for screen printing with which dense CIGS thin films were fabricated under the controlled selenization. The morphology and electrical properties of the thin films were analyzed by SEM images and hall measurement, respectively.

• Journal of Adhesion and Interface
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• v.14 no.2
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• pp.57-67
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• 2013

The incompletion of TIR (Total Internal Reflection) in FTIR (Frustrated Total Internal Reflection) touch screen has been investigated as follows. Assuming a 3 layer thin film of medium1 ($n_1$)-medium2 ($n_2$)-medium3 ($n_3$) with refraction indices of $n_1=n_3{\neq}n_2$, it was theoretically proven that FTIR or OT (ordinary transmission) phenomena might happen through medium2 from medium1 to medium3 relying on relative difference in $n_1(=n_3)$ and $n_2$, and that the formulae for FTIR and OT could be transformed into each other depending on the number state (imaginary or real) of the light wave phase. In parallel to the theoretical analysis, the incompletion of TIR in acrylate due to external contacts was also elucidated from the experimental and phenomenological viewpoints. On the basis of this considerate work, we explained how to improve the touching performance for better FTIR touch screen.

• Current Optics and Photonics
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• v.8 no.3
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• pp.259-269
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• 2024

Optical imaging systems that operate through atmospheric pathways often suffer from image degradation, mainly caused by the distortion of light waves due to turbulence in the atmosphere. Adaptive optics technology can be used to correct the image distortion caused by atmospheric disturbances. However, there are challenges in conducting experiments with strong atmospheric conditions. An optical phase plate (OPP) is a device that can simulate real atmospheric conditions in a lab setting. We suggest a novel two-step process to fabricate an OPP capable of simulating the effects of atmospheric turbulence. The proposed fabrication method simplifies the process by eliminating additional activities such as phase-screen design and phase simulation. This enables an efficient and economical fabrication of the OPP. We conducted our analysis using the statistical fluctuations of the refractive index and applied modal expansion using Kolmogorov's theory. The experiment aims to fabricate an OPP with parameters D/r₀ ≈ 30 and r₀ ≈ 5 cm. The objective is defined with the strong atmospheric conditions. Finally, we have fabricated an OPP that satisfied the desired objectives. The OPP closely simulate turbulence to real atmospheric conditions.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.342.2-342.2
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• 2002

The ${\beta}$-turn has been implicated as an important conformation for biological recognition of peptides or proteins. Benzodiazepine classes have been known as one of the non peptide ${\beta}$-turn mimic scaffolds. We have developed an efficient approach for the synthesis and derivatization of a scaffold of hydroxytetrahydrodizepinone class in order to screen compound library in various protein targets for new lead generations as well as for structure activity relationships of the scaffold. (omitted)