• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1181-1186
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• 2017

The purpose of Demand Response is to reduce the cost of excessive resources and equipment by spontaneous load reductions at peak loads. Having enough power consumers participating in these schemes is key to achieving the goal. Demand Response Aggregator (DRA) is responsible for recruiting demand resources and managing them to participate in reducing the load. DRAs change the price elasticity of demand functions by providing incentives to demand response, thereby affecting price formation in the electricity market. In this paper, this process is modeled to analyze the relationship between DRA's strategic bidding and market outcomes and load reductions. It analyzes the results by applying to competition between DRAs, competition between DR and Gencos, and coexistence of DR load and non-DR load. It is noteworthy that we have found a phenomenon called the Balloon Effect.

• Smart Structures and Systems
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• v.3 no.1
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• pp.69-88
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• 2007

In this study, Field-Programmable Gate Arrays (FPGAs) are investigated as a practical solution to the challenge of designing an optimal platform for implementing algorithms in a wireless sensing unit for structuralhealth monitoring. Inherent advantages, such as tremendous processing power, coupled with reconfigurable and flexible architecture render FPGAs a prime candidate for the processing core in an optimal wireless sensor unit, especially when handling Digital Signal Processing (DSP) and system identification algorithms. This paper presents an effort to create a proof-of-concept unit, wherein an off-the-shelf FPGA development board, available at a price comparable to a microprocessor development board, was adopted. Data processing functions, including windowing, Fast Fourier Transform (FFT), and peak detection, were implemented in the FPGA using a Matlab Simulink-based high-level abstraction tool rather than hardware descriptive language. Simulations and laboratory tests were carried out to validate the design.

• Wind and Structures
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• v.4 no.1
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• pp.73-84
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• 2001

Analysis of pressures measured on the roof of the full-scale Texas Tech building and a 1/50 scale model of a typical house showed that the pressure fluctuations on cladding fastener and cladding-truss connection tributary areas have similar characteristics. The probability density functions of pressure fluctuations on these areas are negatively skewed from Gaussian, with pressure peak factors less than -5.5. The fluctuating pressure energy is mostly contained at full-scale frequencies of up to about 0.6 Hz. Pressure coefficients, $C_p$ and local pressure factors, $K_l$ given in the Australian wind load standard AS1170.2 are generally satisfactory, except for some small cladding fastener tributary areas near the edges.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.186-188
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• 1988

Relaxation spectra of the linear dielectric constants $\varepsilon=\varepsilon'-j{\varepsilon}"$ have been measured as functions of temperature and frequency for alternating copolymers of vinylidene cyanide (VDCN/VAc, VDCN/VPr, VDCN/VBz and VDCN/St) It is found that the linear dielectric constants e show characteristics of the temperature dependence that the real part have a large peak related to the glass transition point(Tg), and of the frequency dependence that the real port increases with decreasing frequency and the imaginary part increases largely in low frequency range. These phenomena mean Debye-type relaxation due to the micro-Brownian moi ions of non-crystalline seqments.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.2
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• pp.77-87
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• 1996

Existing area-based stereo matching algorithms utilize a single rectangular correlation area for computing cross-correlation between corresponding points in stereo images, and compute disparity by finding the peak in the vicinity of depth discontinuity, since, because of inconstnat disparities around discontinuities, the cross-correlation becomes low in such area. Inthis paper, a new area-based matching strategy is proposed exploiting multiple directional correlation masks instead of a single one. The proposed technique computes multiple cross-covariance functions using each oriented mask. Peaks are detected from each covariance function and the disparity is computed by choosing the location with the highest covariance value. Proposed approach can also be applied to compute disparity gradients without obtaining dense depth data. A number of examples are presented using synthetic and natural stereo images.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.895-898
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• 2014

The wavelength dependence of the photoacoustic signal for n-type GaAs semiconductors in the region of the band-gap energies was investigated. The significant changes in the phase and amplitude of the photoacoustic signal near the band-gap absorption wavelengths were observed to occur when the Si-doping densities in GaAs were varied. Particularly, the first derivatives of the photoacoustic phase vs. wavelength graphs were evaluated and fitted with single Gaussian functions. The peak centers and the widths of the Gaussian curves clearly showed linear relationships with the log values of the Si-doping densities in n-type GaAs semiconductors. It is proposed that the wavelength-dependent PA spectroscopy can be used as a simple and nondestructive method for measuring the doping densities in bulk semiconductors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.82-91
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• 1999

A numerical analysis based on the three-dimensional Reynolds-averaged Navier-Stokes equation has been conducted to investigate the flow within a NASA rotor 67 transonic fan. General coordinate transformations are used to represent the complex blade geometry and an H-type grid is used. The governing equations are solved using implicit LU-SGS scheme for the time-marching integration and a standard ${\kappa}-{\varepsilon}$ model is used with wall functions for the turbulence modeling. The computations are compared with the experimental data and a detailed study of the flow structures near peak efficiency and near stall is presented. The calculated overall aerodynamic efficiency and three-dimensional shock system agree well with the laser anemometer data.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.923-929
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• 1999

The cause of optical nonlinearity induced in thermally poled silica glass is believed to be the space charge polarization. Since the second order optical nonlinearity (electro-optic effect) can be used in optical switches the optical nonlinearity in silica glass has drawn a large attention. Space charge polarization occurs when an ionic conducting material is subjected to dc electric field by the blocking electrode. Thermal poling performed to induce the optical nonlinearity in silica glass is basically identical to the process generating space charge polarization. As a first step to understand the mechanism of space charge polarization in silica glass hence the induced optical nonlinearity the absorption currents as functions of time were measured for various types of silica glasses and analyzed by the theory of space charge polarization. It was found that the electrical relaxation exhibited a step by the space charge polarization in the relatively long time range and dielectric loss peak showed a maximum at a specific temperature which is depending on type of silica glass. It was turned out that this relaxation might be a cause of nonlinearity in electrical conductivity of silica glass.

• Journal of Communications and Networks
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• v.2 no.1
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• pp.69-75
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• 2000

A new frame synchronization confirmation technique using a pilot pattern of both uplink and downlink channels is proposed for W-CDMA (Wideband Code Division Multiple Access) system. It is shown that by using this technique, we can cancel the side lobe for autocorrelation functions of the frame synchronization words of pilot pattern have the maximum to-of-phase autocorrelation value "4" with two peak values equal in magnitude and opposite in polarity at zero and middle shifts. Due to this side lobe cancellation effect, therefore, the autocorrelation function of the frame synchronization words becomes ideal for the frame synchronization confirmation since double maximum correlation values equal in magnitude and opposite polarity at zero ad middle shifts can be achieved. This property can be used to double check frame synchronization timing and thus. improve the frame synchronization confirmation performance.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.181.2-181
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• 2001

Stereo PACS (Picture Archiving and Communication System) is not available yet because of some limitations of medical stereo image software and viewing devices. As a stereo PACS viewer, we designed two functions. One is selecting and viewing a multiplexed stereo image directly, and the other is selecting a stereo pair image (left and right sides both) and merging the stereo pair image into a multiplexed image in software. For the medical image compression of 3-D stereo endoscopic images, we used JPEG and Wavelet compression and to determine an acceptable compression rate using PSNR (Peak Signal-to-Noise Ratio). As a result, we got the conclusion that medically acceptable image compression rate should have the PSNR of above about 40[dB] (JPEG (5:1), Wavelet (10:1)).