• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1694-1696
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• 2004

$Si_3N_4$ 박막을 동일한 공정 파라메터로 저압 화학기상증착법(LPCVD)으로 증착하고, IS, LOCOS- IS 및 ISFET의 세 가지 각각 다른 구조로 하여 용약 중 pH 농도 감지용 센서소자를 제작하였다. 이 세 가지 다른 센서소자에 대하여 pH 농도변화에 따른 감지도, 감지특성곡선의 선형성, 히스테리시스 등 주요 특성을 각각 조사한 후 비교 분석하였다. LOCOS-IS 구조의 pH 센서는 ISFET 구조의 pH 센서와 유사한 우수한 제반 pH 감지특성을 보였으나, 간단한 IS 구조의 pH 센서는 이들에 비해 상대적으로 열악한 pH 감지특성을 보였다. 동일공정으로 제작된 Si3N4 박막으로 제작되었음에도 불구하고 간단한 IS 구조의 pH 센서의 비교적 열악한 특성을 보이는 원인을 규명하기 위하여, pH 농도 변화에 따른 C-V특성 변화에 의한 pH 감지특성 조사시의 IS 및 LOCOS-IS 구조의 정전용량의 변화를 비교하고 고찰하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.125-133
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• 2006

This paper presents comparison results of Step Response Model of Dynamic Matrix Control(DMC) for a drum-type boiler-turbine system of a fossil power plant. Two possible kinds of step response models are investigated in designing the DMC, one is developed with the linearization of theoretical model and the other is developed with the process step-test data. Then, the control performances of each model-based DMC are simulated and evaluated. It is observed that the simulation results with the step-response model based on the test data show satisfactory results, while the linearized model is not suitable for the control of boiler-turbine system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.82-88
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• 2009

Power capacitor is generally installed to compensate for the low power factor of inductive load But it has been used as passive filter to reduce harmonics generated by the power conversion device. Passive filter is composed by the series connection of reactor and capacitor. Because passive filter has play an important role on the absorber of harmonics, it takes voltage and current stress, follows partially burned on flamed and degradation, finally it has not guaranteed normal life. In this paper, we analyzed the effect that passive filter installed at the source side of PWM inverter is received by harmonics absorption.

• Science of Emotion and Sensibility
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• v.13 no.2
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• pp.391-402
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• 2010

In this study, breathable waterproof materials were prepared by electrospinning. Five kinds of electrospun nanofiber web layered systems with different levels of nanofiber web density, as well as different substrates and layer structures were fabricated, and their mechanical properties (tensile, bending, shear, compression, surface, and thickness & weight) were measured by the KES-FB system and compared with those of conventional breathable waterproof fabrics (densely woven fabric, PTFE laminated fabric and PU coated fabric). The KES-FB measurements demonstrate that the lab-scale nanofiber web layered systems are more flexible and fuller than commercial nanofiber web layered systems, which have a more compact structure than the lab-scale nanofiber web layered systems. Densely woven fabrics and lab-scale nanofiber web layered systems showed lower values of tensile linearity (LT), bending stiffness (B), and shear stiffness (G) than those of PU coated and PTFE laminated fabric. These results indicate that they are more flexible and have less resistance to the shearing movement, corresponding to a more pliable material having a better drape, than PU coated fabrics and PTFE laminated fabrics.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.286-291
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• 2007

We theoretically investigated the far-field radiation pattern of epi-signal from a polystyrene sphere in coherent anti-Stokes Raman scattering (CARS) microscopy with an objective lens of high numerical aperture. We calculated the field distribution of the incident laser beams under the tight-focusing condition and the far-field radiation pattern through coherent addition of radiation from the nonlinear polarizations (Hertzian dipoles) as the origin of CARS signal generation. The epi-radiation patterns for polystyrene spheres of different diameters are calculated, and the pattern of a sphere is also compared with that of a shell fer a diameter of 1100 nm. We finally show how the radiation pattern of the polystyrene sphere changes as the center of the sphere shifts from the focus of the beam.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.24-31
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• 1999

Ammonia gas sensors were fabricated with ZnO-based thin films grown by RF-magnetron sputtering method. The films which were doped with $MoO_3$ catalysts of various weight percents were grown in different sputtering gases to fabricate the sensors with a high sensitivity, low working temperature and rapid response time. To improve electrical stability, the films were aged in various conditions. The sensors doped with the catalysts and grown in oxygen sputtering gas showed the improvement of sensitivity. These exhibited the increase of surface carrier concentration and electron mobility. The sensor with 0.875wt.% $MoO_3$ catalysts showed the maximum sensitivity of 70 in ammonia gas concentration of 160 ppm at a working temperature of $300^{\circ}C$. The sensor which is aged at $330^{\circ}C$ for 72hrs in oxygen ambient exhibited tourer sensitivity of 57, but more stable properties, excellent linearity.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.154-161
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• 2009

A fuel cell power plant is a very complex system which has various control loops with some non-linearity. For control of a fuel cell power plant, dynamic models of fuel cell stacks have been developed and simplified process flow diagrams of a fuel cell power plant has been presented. Using such a model of a Molten Carbonate Fuel Cell (MCFC) power plant, this paper deals with development of an intelligent setpoint reference governor (I-SRG) to find the optimal setpoints and feed forward control inputs for the plant power demand. The I-SRG is implemented with neural network by using Particle Swarm Optimization (PSO) algorithm based on system constraints and performance objectives. The feasibility of the I-SRG is shown through simulation of an MCFC power plant for tracking control of its power demand.

• Journal of IKEEE
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• v.26 no.3
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• pp.349-354
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• 2022

In thermal power plants, boiler models have been used widely in evaluating logic configurations, performing system tuning and applying control theory, etc. Furthermore, proper plant models are needed to design the accurate controllers. Sometimes, mathematical models can not exactly describe a power plant due to time varying, nonlinearity, uncertainties and complexity of the thermal power plants. In this case, a neural network can be a useful method to estimate such systems. In this paper, the models of boiler steam system in a thermal power plant are developed by using a generalized regression neural network(GRNN). The models of the superheater, reheater, attemperator and drum are designed by using GRNN and the models are trained and validate with the real data obtained in 540[MW] power plant. The validation results showed that proposed models agree with actual outputs of the drum boiler well.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.54-61
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• 1999

This paper proposes a new optic link structure applicable to broad-band wireless access microcellularsystem servicing in the millimeter wave frequency band. The proposed structure utilizes photonic mixing by exploiting the nonlinear property of EOMs, which leads to the frequency up-conversion at the CS and thus, electrical mixing at a BS is not required. Moreover, via transmitting an additional optical millimeter wave carrier into the Bs, the dispenses with an active optic source, which miniaturizes the BS. We analyze CNR, IM3/C in the downlink and SFDR in the uplink. Through simulation using the typical parameter values we also show the feasibility of the proposed system based on the requirements in the current microcellular system.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.466-471
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• 1994

The polymeric titania sol was prepared via partial hydrolysis of titanium isopropoxide and its characteristics were investigated. The effect of solvent, catalyst and water content on the sol stability was investigated. The shear viscosities of sol solution at different temperatures were measured to determine the gel time. Employing the spin coating technique, optically clear and transparent titanium oxide thin film was fabricated. Even after doped with second-order nonlinear optical(NL0) active monomers, the film quality was maintained very homogeneous. The film was corona-poled under 3~ 5kV at 50~$100^{\circ}C$ range. The electro-optic coefficient, $r_{33}$ was measured to be 1.5~5pm/V using the wavelength, 632.8nm from He-Ne laser.