• Journal of Ocean Engineering and Technology
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• v.34 no.6
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• pp.419-427
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• 2020

In this study, a particle image velocimetry (PIV)-based pressure estimation method was investigated, with application to the wave-in-deck loading phenomenon. An experimental study was performed in a two-dimensional wave tank using a fixed deck structure under a focused wave, obtaining local pressures by pressure sensors, global loads by load cells, and instantaneous velocity fields using the PIV measurement technique. The PIV-based pressure estimation method was applied using the Euler equation as the governing equation, and the proper time step for the wave impact pressure was studied using the normalized root-mean-square deviation. The pressure estimation method showed good agreement for the local impact pressure in comparison with the measured pressure by the pressure sensors. However, some differences were observed in the peak pressure due to the limitations of the Euler equation and the sampling rate of the measurement system. Using the estimation method, the pressure fields during wave-in-deck loading were determined in the study, with an analysis of the mechanism of impact and negative pressure occurrence.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.114-126
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• 2009

In this paper, we propose a PSNR(peak-to-peak signal to noise ratio) estimation method exploiting visual rhythm information for the reconstructed video frames at the customer's STB(Set-top Box). Key idea is that we can estimate the PSNR by using VR(visual rhythm) information even though a VR consists of the pixels in a vertical direction of a 2D(2-dimensional) video frame, because VR is the 1D projected version of a 2D video frame approximately. Simulation results show that the estimated PSNR from VR information is closely related to the PSNR from 2D video frames. The advantages of the proposed scheme includes that it can monitor the video quality efficiently while minimizing the computation load of STB, and show the location, duration and occurrence count of severe picture degradation.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.1 s.24
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• pp.39-46
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• 2007

The blasting load induced by the explosion of the powder generation the vibration of the ground and affects on nearby ground and underground structures. The structures are possibly damaged and it may create the social problems such as noneconomic construction due to the delay of the construction period especially in urban areas. Therefore, the stability of the nearby structures need to be evaluated. In this study, the stability of the tunnel is estimated and examined by the analytical solution and by using $FLAC^{2D}$ which is one of the programs based on the finite difference analysis.

• ETRI Journal
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• v.41 no.6
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• pp.715-730
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• 2019

We propose a switched beam-forming antenna that satisfies not only ultra-wideband characteristics but also beam-forming in the WLAN frequency band using an ultra-wideband antenna and passive parasitic elements applying a broadband optimal reactance load algorithm. We design a power and phase estimation function and an error correction function by re-analyzing and normalizing all the components of the parasitic array using control system engineering. The proposed antenna is compared with an antenna with a pin diode and reactance load value, respectively. The pin diode is located between the passive parasitic elements and ground plane. An antenna beam can be formed in eight directions according to the pin diode ON (reflector)/OFF (director) state. The antenna with a reactance load value achieves a better VSWR and gain than the antenna with a pin diode. We confirm that a beam is formed in eight directions owing to the RF switch operation, and the measured peak gain is 7 dBi at 2.45 GHz and 10 dBi at 5.8 GHz.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.982-984
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• 1997

DSM activities have grown and matured over several years in Korea. KEPCO is currently offering some DSM programs in industrial, commercial, and residential customers such as rebate program in purchasing efficient measures. The systematic evaluation process of energy savings and peak reduction will be very important for deciding on the optimal investment of DSM activities in utilities in the future. In general, the estimation process of the potential savings of DSM activities include the determination of baseline electricity consumption, the instantaneous technical potential (ITP), the phased technical potential (PTP), the economic potential (EP), and the achievable potential (AP). The purpose of this article is to provide evaluation process of those DSM potential savings based on bottom-up approach and applicate to residential sector in Korea. In case study, ITP, EP are estimated to be respectively 21.5%, 5.7% of total energy consumption, and 4.1%, 2.5% of peak load in 2010.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.4
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• pp.287-293
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• 2004

This paper proposes an efficient motion compensation algorithm for video sequences with brightness variations. In the proposed algorithm, the brightness variation parameters are estimated and local motions are compensated. To detect the frame with large brightness variations, we employ the frame classification based on the cross entropy between histograms of two successive frames, which can reduce the computational redundancy. Simulation results show that the proposed method yields a higher peak signal to noise ratio (PSNR) than that of the conventional methods, with a low computational load, when the video scene contains large brightness changes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.623-628
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• 2007

The accurate peak response estimation of a seismically excited structure with frictional damping system(FDS) is very difficult since the structure with FDS shows nonlinear behavior dependent on the structural period, loading characteristics, and relative magnitude between the frictional force and the excitation load. Previous studies have estimated that by replacing a nonlinear system with an equivalent linear one or by employing the response spectrum obtained based on nonlinear time history and statistical analysis. In the case that an earthquake load is defined with probabilistic characteristics, the corresponding response of the structure with FDS has probabilistic distribution. In this study, nonlinear time history analyses were performed for the structure with FDS subjected to artificial earthquake loads generated using Kanai-Tajimi filter. An equation for the probability density function (PDF) of the displacement response is proposed by adapting the PDF of the normal distribution. Finally, coefficients of the proposed PDF are obtained by regression analysis of the statistical distribution of the time history responses. Finally the correlation between PDFs and statistical response distribution is presented.

• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.241-252
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• 2015

Runoff behaviors by five bias correction methods were analyzed, which were Change Factor methods using past observed and estimated data by the estimation scenario with average annual calibration factor (CF_Y) or with average monthly calibration factor (CF_M), Quantile Mapping methods using past observed and estimated data considering cumulative distribution function for entire estimated data period (QM_E) or for dry and rainy season (QM_P), and Integrated method of CF_M+QM_E(CQ). The peak flow by CF_M and QM_P were twice as large as the measured peak flow, it was concluded that QM_P method has large uncertainty in monthly runoff estimation since the maximum precipitation by QM_P provided much difference to the other methods. The CQ method provided the precipitation amount, distribution, and frequency of the smallest differences to the observed data, compared to the other four methods. And the CQ method provided the rainfall-runoff behavior corresponding to the carbon dioxide emission scenario of SRES A1B. Climate change scenario with bias correction still contained uncertainty in accurate climate data generation. Therefore it is required to consider the trend of observed precipitation and the characteristics of bias correction methods so that the generated precipitation can be used properly in water resource management plan establishment.

• Steel and Composite Structures
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• v.20 no.4
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• pp.777-799
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• 2016

One of the major components for performance based seismic design is accurate estimation of critical seismic demand parameters. While nonlinear seismic analysis is the most appropriate analysis method for estimation of seismic demand parameters, this method is very time consuming and complex. Single mode pushover analysis method, N2 method and multi-mode pushover analysis method, modal pushover analysis (MPA) are two nonlinear static methods that have recently been used for seismic performance evaluation of few lateral load-resisting systems. This paper further investigates the applicability of N2 and MPA methods for estimating the seismic demands of ductile unstiffened steel plate shear walls (SPSWs). Three different unstiffened SPSWs (4-, 8-, and 15-storey) designed according to capacity design approach were analysed under artificial and real ground motions for Vancouver. A comparison of seismic response quantities such as, height-wise distribution of floor displacements, storey drifts estimated using N2 and MPA methods with more accurate nonlinear seismic analysis indicates that both N2 and MPA procedures can reasonably estimates the peak top displacements for low-rise SPSW buildings. In addition, MPA procedure provides better predictions of inter-storey drifts for taller SPSW. The MPA procedure has been extended to provide better estimate of base shear of SPSW.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.3
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• pp.421-425
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• 2018

The icebreaking research vessel ARAON performed ice field tests during her 2016 Arctic voyage. The ship is subjected to ice loads through ice-ship interaction processes. Local ice load acting on ARAON's bow section was measured by using stain gauges installed on the inner hull plates and transverse frames of bow section. In this paper the local ice loads at transverse frames estimated from shear strain data were compared to ice loads from hull plate pressures by using the influence coefficient method. In addition to the analysis of local ice loads, the characteristics of peak ice loads with the ship speed is also discussed. It is recommended that the local ice loads estimated by calculating shear forces acting on transverse frames may be useful in estimating local ice loads on the hull of ship.