• Journal of the Earthquake Engineering Society of Korea
• /
• v.21 no.4
• /
• pp.189-195
• /
• 2017

In the seismic design of building structural members, due to the complexity of the placement of PC steels in prestressed concrete members, it is necessary to review and define the definition of member damage in comparison with reinforced concrete members. In this study, the results of past experiments compared with the calculation results by 'section Analysis Method', with the aim of reviewing the precision of calculation results when member damage evaluation is performed using the section analysis method. Furthermore, it is also compared with the calculation results by the 'split Element Method'. In addition, parametric studies were carried out, and the influence of the difference between the amount of PC steels and reinforced bar on the residual strain was examined.

• 유체기계공업학회:학술대회논문집
• /
• 2001.11a
• /
• pp.106-112
• /
• 2001

This paper presents analysis of the flows through three different types of radial compressor impeller by using quasi-three-dimensional analysis method. The method obtains two-dimensional solution for velocity distribution on meridional plane, and then calculates approximately the static pressure distributions on blade surfaces. Finite difference method is used for the solutions of governing equations. The compressors have low level compression-ratio and 12 straight radial blades with no sweepback. The results are compared with experimental data and the results of inviscid analysis with finite element method. It can be concluded that the agreement is good for the cases where viscous effects are not dominant.

• Structural Engineering and Mechanics
• /
• v.4 no.2
• /
• pp.177-190
• /
• 1996

A method to numerically evaluate the behaviour of single span beams, prestressed with external tendons and symmetrically loaded is presented. This algorithm, based on the Finite Difference Method, includes second order effects and large displacements in an attempt to more fully understand the behaviour of the beam up to collapse. The numerical technique discussed is particularly appropriate for the analysis of R.C. and P.C. beams rehabilitated or strengthened by means of external prestressing but it is reliable for the analysis of new beams as well.

• Journal of electromagnetic engineering and science
• /
• v.2 no.2
• /
• pp.81-86
• /
• 2002

This paper presents the full wave analysis of microwave circuits with nonlinear device using the finite difference time domain method. The equivalent current source is used to model nonlinear device and all the electric field components at the nonlinear device are updated by FDTD algorithm. The currents and voltages of nonlinear device are calculated by the state equations and iteration method. To validate the proposed method, the S-parameters of NEC NE72089 MESFET in various conditions are analyzed and the results are compared with those of the ADS. The proposed method is applied to the analysis of a microwave amplifier, which includes NEC NE72089 MESFET. The analysis results obtained by the present method show good agreement with those of the ADS.

• Geomechanics and Engineering
• /
• v.6 no.6
• /
• pp.545-560
• /
• 2014

For slope stability analysis, an alternative to the classical limit equilibrium method (LEM) of slices is the shear strength reduction method (SRM), which can be integrated into finite element analysis or finite difference analysis. Recently, probabilistic analysis of earth slopes has been very attractive because it is capable to take the soil uncertainty into account. However, the SRM is less commonly extended to probabilistic framework compared to a variety of probabilistic LEM analysis of earth slopes. To overcome some limitations that hinder the development of probabilistic SRM stability analysis, a new procedure based on recursive algorithm FORM with sensitivity analysis in the space of original variables is proposed. It can be used to deal with correlated non-normal variables subjected to implicit limit state surface. Using the proposed approach, a probabilistic finite element analysis of the stability of an existing earth dam is carried out in this paper.

• Korean Journal of Remote Sensing
• /
• v.35 no.4
• /
• pp.561-571
• /
• 2019

In this paper, we analyze the effect of the representative spectral indices, normalized difference vegetation index (NDVI), normalized difference water index (NDWI) and normalized difference built-up index (NDBI) on classification accuracies of Landsat-8 OLI image.After creating these spectral index images, we propose five methods to select the spectral index images as classification features together with Landsat-8 OLI bands from 1 to 7. From the experiments we observed that when the spectral index image of NDVI or NDWI is used as one of the classification features together with the Landsat-8 OLI bands from 1 to 7, we can obtain higher overall accuracy and kappa coefficient than the method using only Landsat-8 OLI 7 bands. In contrast, the classification method, which selected only NDBI as classification feature together with Landsat-8 OLI 7 bands did not show the improvement in classification accuracies.

• Management & Information Systems Review
• /
• v.27
• /
• pp.53-69
• /
• 2008

In this paper we analyse performance of value strategy and moving average method among the non-financial listed companies whose fiscal year ends at December in the Korean Stock Exchange between 1996 and 2005. And we analyse combination investment performance of value investment and moving average method. After the analysis objective enterprises divide with the value stock and the growth stock, in accordance with moving average method we divide ascending stock and descending stock. And we compose 6 portfolios with combination of value stock, growth stock, ascending stock and descending stock. Using the difference of investment performance of these portfolios, when fundamental analysis and technical analysis method all considering we measure investment performance. The major findings of this research are as follows: First, the value strategy of buying value stocks and selling growth stocks were effective in the long-term investment. Second, using the moving average method, technical analysis were effective in the case of the short-term investment. Third, the portfolios combined fundamental analysis and technical analysis were more effective than investment performance of technical analysis.

• Journal of Korea Water Resources Association
• /
• v.55 no.9
• /
• pp.701-705
• /
• 2022

Reliable drought inflow scenarios are required to plan reservoirs in response to the present severe drought-like conditions. However, the previously developed method for generating drought inflows, the K-water cumulative difference method (KCM), is considered inadequate owing to its potential for negative inflow, reversal phenomena, and overestimation. Nevertheless, the occurrence of these aspects has not been theoretically analyzed. Hence, this study employed the quantile function and frequency factor for log-normal and Gumbel distributions to quantify the contributing factors of these limitations. Consequently, it was found that the negative inflows are generated when the difference in the location parameters, during the accumulation process, exceeds that of the scale parameters. In addition, as the standard deviation decrease during the accumulation process, the reversal phenomena, and inflated values prevailed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.7 s.178
• /
• pp.1847-1853
• /
• 2000

A computer simulation technique for 2-dimensional laser generated ultrasonic waves was developed for visualization and investigation of ultrasonic propagation in solids. The technique is similar to a finite difference method (FDM) and a mass-particle model method, but uses a new nodal calculation method based on fundamental consideration of an elastic wave equation. By this method, the propagation behavior oflaser generated ultrasonic wave in thermoelastic and ablation mode is visualized and shows good agreement with previous experimental result or the numerical analysis result by Green function.

• Korean Journal of Remote Sensing
• /
• v.36 no.5_3
• /
• pp.1067-1076
• /
• 2020

In this paper, an unsupervised saliency guided change detection method using UAV and aerial imagery is proposed. Regions that are more different from other areas are salient, which make them more distinct. The existence of the substantial difference between two images makes saliency proper for guiding the change detection process. Change Vector Analysis (CVA), which has the capability of extracting of overall magnitude and direction of change from multi-spectral and temporal remote sensing data, is used for generating an initial difference image. Combined with an unsupervised CVA and the saliency, Principal Component Analysis(PCA), which is possible to implemented as the guide for change detection method, is proposed for UAV and aerial images. By implementing the saliency generation on the difference map extracted via the CVA, potentially changed areas obtained, and by thresholding the saliency map, most of the interest areas correctly extracted. Finally, the PCA method is implemented to extract features, and K-means clustering is applied to detect changed and unchanged map on the extracted areas. This proposed method is applied to the image sets over the flooded and typhoon-damaged area and is resulted in 95 percent better than the PCA approach compared with manually extracted ground truth for all the data sets. Finally, we compared our approach with the PCA K-means method to show the effectiveness of the method.