• Journal of Environmental Science International
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• v.25 no.12
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• pp.1653-1660
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• 2016

Drought is a reoccurring worldwide natural hazard that affects not only food production but also economics, health, and infrastructure. Drought monitoring is usually performed with precipitation-based indices without consideration of the actual state and amount of the land surface properties. A drought index based on the actual evapotranspiration can overcome these shortcomings. The severity of a drought can be quantified by making a spatial map. The procedure for estimating actual evapotranspiration is costly and complicated, and requires land surface information. The possibility of utilizing drone-driven remotely sensed data for actual evapotranspiration estimation was analyzed in this study. A drone collected data was used to calculate the normalized difference vegetation index (NDVI) and soil-adjusted vegetation index (SAVI). The spatial resolution was 10 m with a grid of $404{\times}395$. The collected data were applied and parameterized to an actual evapotranspiration estimation. The result shows that drone-based data is useful for estimating actual evapotranspiration and the corresponding drought indices.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.16 no.1
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• pp.72-80
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• 2016

Re-auction happens when a bid winner defaults on the payment without making second in-line purchase declaration even after determining sales permission. This is a process of selling under the court's authority. Re-auctioning contract price of real estate is largely influenced by the real estate business, real estate value, and the number of bidders. This paper is designed to establish a statistical model that deals with the number of bidders participating especially in apartment re-auctioning. For these, diverse factors are taken into consideration, including ratio of minimum sales value from the point of selling to re-auctioning, number of bidders at the time of selling, investment value of the real estate, and so forth. As an attempt to consider ambiguous and vague factors, this paper presents a comparatively vague concept of real estate and bidders as trapezoid fuzzy number. Two different methods based on the least squares estimation are applied to fuzzy regression model in this paper. The first method is the estimating method applying substitution after obtaining the estimators of regression coefficients, and the other method is to estimate directly from the estimating procedure without substitution. These methods are provided in application for re-auction data, and appropriate performance measure is also provided to compare the accuracies.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.245-252
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• 2013

Leaf area index (LAI) is important in explaining the ability of crops to intercept solar energy for biomass production, amount of plant transpiration, and in understanding the impact of crop management practices on crop growth. This paper describes a procedure for estimating LAI as a function of image-derived vegetation indices from temporal series of RapidEye imagery obtained from 2010 to 2012 using empirical models in a rice plain in Seosan, Chungcheongnam-do. Rice plants were sampled every two weeks to investigate LAI, fresh and dry biomass from late May to early October. RapidEye images were taken from June to September every year and corrected geometrically and atmospherically to calculate normalized difference vegetation index (NDVI). Linear, exponential, and expolinear models were developed to relate temporal satellite NDVIs to measured LAI. The expolinear model provided more accurate results to predict LAI than linear or exponential models based on root mean square error. The LAI distribution was in strong agreement with the field measurements in terms of geographical variation and relative numerical values when RapidEye imagery was applied to expolinear model. The spatial trend of LAI corresponded with the variation in the vegetation growth condition.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.130-137
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• 2008

This paper presents high resolution techniques of three-dimensional(3D) scattering center extraction for a radar backscattered signal in radar target recognition. We propose a 3D pairing procedure, a new approach to estimate 3D scattering centers. This pairing procedure is more accurate and robust than the general criterion. 3D MEMP(Matrix Enhancement and Matrix Pencil) with the 3D pairing procedure first creates an autocorrelation matrix from radar backscattered field data samples. A matrix pencil method is then used to extract 3D scattering centers from the principal eigenvectors of the autocorrelation matrix. An autocorrelation matrix is constructed by the MSSP(modified spatial smoothing preprocessing) method. The observation matrix required for estimation of 3D scattering center locations is built using the sparse scanning order conception. In order to demonstrate the performance of the proposed technique, we use backscattered field data generated by ideal point scatterers.

• Structural Engineering and Mechanics
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• v.59 no.3
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• pp.455-473
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• 2016

Methods for the seismic demands evaluation of structures require iterative procedures. Many studies dealt with the development of different inelastic spectra with the aim to simplify the evaluation of inelastic deformations and performance of structures. Recently, the concept of inelastic spectra has been adopted in the global scheme of the Performance-Based Seismic Design (PBSD) through Capacity-Spectrum Method (CSM). For instance, the Modal Pushover Analysis (MPA) has been proved to provide accurate results for inelastic buildings to a similar degree of accuracy than the Response Spectrum Analysis (RSA) in estimating peak response for elastic buildings. In this paper, a simplified nonlinear procedure for evaluation of the seismic demand of structures is proposed with its applicability to multi-degree-of-freedom (MDOF) systems. The basic concept is to write the equation of motion of (MDOF) system into series of normal modes based on an inelastic modal decomposition in terms of ductility factor. The accuracy of the proposed procedure is verified against the Nonlinear Time History Analysis (NL-THA) results and Uncoupled Modal Response History Analysis (UMRHA) of a 9-story steel building subjected to El-Centro 1940 (N/S) as a first application. The comparison shows that the new theoretical approach is capable to provide accurate peak response with those obtained when using the NL-THA analysis. After that, a simplified nonlinear spectral analysis is proposed and illustrated by examples in order to describe inelastic response spectra and to relate it to the capacity curve (Pushover curve) by a new parameter of control, called normalized yield strength coefficient (${\eta}$). In the second application, the proposed procedure is verified against the NL-THA analysis results of two buildings for 80 selected real ground motions.

• Journal of Korea Water Resources Association
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• v.47 no.1
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• pp.83-93
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• 2014

This research was carried out for suggesting design criteria and procedure for maximizing flood control capacity by building flood control facilities like flood retention basin built in connection with existing facilities in order to cope with increased uncertainty due to factors such as urbanization and climate change. We suggested the procedure for the analysis under the various scenarios applicable for the cases of determining retention basin capacity as provision for the flood water level increase in main river channel or estimating flood water level reduction effect when retention basin capacity is given. Procedure for estimating design flood hydrograph at any duration using Intensity-Duration-Quantity (IDQ) originated from the existing IDF, and its application example were provided. Based on rainfall estimated by the IDQ analysis, it is possible to calculate an equivalent peak hydrographs under various scenarios, e.g. lower frequency hydrograph under same rainfall duration with water level higher than existing hydrograph, hydrograph with same peak and higher volume due to increased rainfall duration, hydrograph with higher peak and volume than existing hydrograph, etc.

• ETRI Journal
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• v.35 no.5
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• pp.849-858
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• 2013

In this paper, we propose a new adaptive single model to track a maneuvering target with abrupt accelerations. We utilize the stochastic differential equation to model acceleration of a maneuvering target with stochastic volatility (SV). We assume the generalized autoregressive conditional heteroscedasticity (GARCH) process as the model for the tracking procedure of the SV. In the proposed scheme, to track a high maneuvering target, we modify the Kalman filtering by introducing a new GARCH model for estimating SV. The proposed tracking algorithm operates in both the non-maneuvering and maneuvering modes, and, unlike the traditional decision-based model, the maneuver detection procedure is eliminated. Furthermore, we stress that the improved performance using the GARCH acceleration model is due to properties inherent in GARCH modeling itself that comply with maneuvering target trajectory. Moreover, the computational complexity of this model is more efficient than that of traditional methods. Finally, the effectiveness and capabilities of our proposed strategy are demonstrated and validated through Monte Carlo simulation studies.

• 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.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.388-395
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• 2005

A numerical procedure is proposed as a mesh-size insensitive structural stress definition that gives a stress state at a weld toe with relatively large mesh size. The structural stress values obtained using different finite element types, i.e. shell element and solid element, are examined for typical weld structures. The calculation procedures are performed using the balanced nodal forces and moments obtained from finite element solutions. A consistent formulation based on work equivalent argument has been implemented to transform the balanced nodal forces and moments from shell to line force and line moments at each nodal position. The mesh-insensitivity, the effect of distance $\delta$(where the stress is calculated) and the potential limitations of the structural stress method are examined for various types of weldments. Based on the results from this study, it is expected to develop a more precise stress estimation technique for fatigue strength assessment of welded structures.

• Korean Journal of Poultry Science
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• v.47 no.2
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• pp.107-114
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• 2020

This study was conducted to investigate the variation in nutrient composition of oilseed meals and to develop prediction equations for amino acid concentrations. Energy and nutrient contents were determined in a total of 1,380 feed ingredient samples including copra byproducts, corn distillers, dried grains with solubles, palm kernel byproducts, and soybean meal. The ingredient samples were imported to the Republic of Korea between 2006 and 2015. Data were analyzed using the MIXED procedure of SAS. The regression procedure of SAS was used to generate the prediction equation for the lysine concentration using the crude protein (CP) concentration as an independent variable. The concentrations of moisture, gross energy, CP, ether extract, crude fiber, ash, calcium, phosphorus, lysine, methionine, cysteine, and threonine in tested oilseed meals differed (P<0.05) depending on producing countries. The prediction equations for amino acid concentrations (% as-is basis) in the oilseed meals are: lysine = -1.08 + 0.080 × CP (root mean square error = 0.244, R² = 0.924, and P<0.001); threonine = -0.297 + 0.044 × CP (root mean square error = 0.099, R² = 0.958, and P<0.001). In conclusion, energy and nutrient compositions vary in the oilseed meals depending on the producing countries. Moreover, the crude protein concentration can be used as a suitable independent variable for estimating lysine and threonine concentrations in the oilseed meals.