• Steel and Composite Structures
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• 제49권1호
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• pp.65-79
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• 2023

This paper presents a development of empirical evaluations, which can be used to evaluate the damage of fiber-reinforced concrete composites (FRC) wall subjected to close-in blast loads. For this development, a combined application of numerical simulation and machine learning approaches are employed. First, finite element modeling of FRC wall under blast loading is developed and verified using experimental data. Numerical analyses are then carried out to investigate the dynamic behavior of the FRC wall under blast loading. In addition, a data set of 384 samples on the damage of FRC wall due to blast loads is then produced in order to develop machine learning models. Second, three robust machine learning models of Random Forest (RF), Support Vector Machine (SVM), and Extreme Gradient Boosting (XGBoost) are employed to propose empirical evaluations for predicting the damage of FRC wall. The proposed empirical evaluations are very useful for practical evaluation and design of FRC wall subjected to blast loads.

• 천문학회지
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• 제29권spc1호
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• pp.239-240
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• 1996

Precise masses, radii, and luminosities from eclipsing binaries and colour-magnitude diagrams for open clusters are classic tools in empirical tests of stellar evolution models. We review the accuracy and completeness required for such data to discriminate between current models and describe some recent. results with implications for convection theory.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.172-172
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• 2020

In recent years, soil erosion has come to be regarded as an essential environmental problem in human life. Soil erosion causes various on- and off-site problems such as ecosystem destruction, decreased agricultural productivity, increased riverbed deposition, and deterioration of water quality in streams. To solve these problems caused by soil erosion, it is necessary to quantify where, when, how much soil erosion occurs. Empirical erosion models such as the Universal Soil Loss Equation (USLE) family models have been widely used to make spatially distributed soil erosion vulnerability maps. Even if the models detect vulnerable sites relatively well by utilizing big data related to climate, geography, geology, land use, etc. within study domains, they do not adequately describe the physical process of soil erosion on the ground surface caused by rainfall or overland flow. In other words, such models remain powerful tools to distinguish erosion-prone areas at the macro scale but physics-based models are necessary to better analyze soil erosion and deposition and eroded particle transport. In this study, the physics-based Surface Soil Erosion Model (SSEM) was upgraded based on field survey information to produce sediment yield at the watershed scale. The modified model (hereafter MoSE) adopted new algorithms on rainfall kinematic energy and surface flow transport capacity to simulate soil erosion more reliably. For model validation, we applied the model to the Doam dam watershed in Gangwon-do and compared the simulation results with the USLE outputs. The results showed that the revised physics-based soil erosion model provided more improved and reliable simulation results than the USLE in terms of the spatial distribution of soil erosion and deposition.

• The Journal of Asian Finance, Economics and Business
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• 제8권11호
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• pp.1-10
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• 2021

This paper compares the performance of Fama-French three-factor and five-factor models using a dataset of 20 Pakistani commercial banks for the period 2011 to 2020. We focus on an emerging economy as the findings from earlier studies on developed countries cannot be generalized in emerging markets. For empirical analysis, twelve portfolios were developed based on size, market capitalization, investment strategy, and growth. Subsequently, we constructed five Fama-French factors namely, R_M, SMB, HML, RMW, and CMA. The OLS regression technique with robust standard errors was applied to compare the predictive power of both the Fama-French models. Further, we also compared the mean-variance efficiency of the Fama-French models through the GRS test. Our empirical analysis provides three unique and interesting findings. First, both asset pricing models have similar predictive power to explain the expected portfolio returns in most cases. Second, our results from the GRS test suggest that there is no noticeable difference in the mean-variance efficiency of one asset pricing model over the other. Third, we find that all factors of both Fama-French models are statistically significant and are important for explaining the volatility of expected commercial bank returns in the context of Pakistan.

• Geomechanics and Engineering
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• 제30권5호
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• pp.437-448
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• 2022

Alluvial soil is challenging to work with due to its high compressibility. Thus, consolidation settlement of this type of soil should be accurately estimated. Accurate estimation of the consolidation settlement of alluvial soil requires accurate prediction of compressibility parameters. Geotechnical engineers usually use empirical correlations to estimate these compressibility parameters. However, no attempts have been made to develop correlations to estimate compressibility parameters of alluvial soil. Thus, this paper aims to develop new models to predict the compression and recompression indices (Cc and Cr) of alluvial soils. As part of the study, geotechnical laboratory tests have been conducted on large number of undisturbed samples of local alluvial soil. The obtained results from these tests in addition to available results from the literature from different parts in the world have been compiled to form the database of this study. This database is then employed to examine the accuracy of the available empirical correlations of the compressibility parameters and to develop the new models to estimate the compressibility parameters using the nonlinear regression analysis. The accuracy of the new models has been accessed using mean absolute error, root mean square error, mean, percentage of predictions with error range of ±20%, percentage of predictions with error range of ±30%, and coefficient of determination. It was found that the new models outperform the available correlations. Thus, these models can be used by geotechnical engineers with more confidence to predict Cc and Cr.

• East Asian Economic Review
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• 제20권3호
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• pp.279-309
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• 2016

The proposed Trans-Pacific Partnership (TPP) is a free trade agreement among 12 Pacific Rim countries whose joint gross domestic products (GDPs) account for 36 percent of world GDP and whose mutual trade accounts for approximately 24 percent of world trade. As for most proposed free trade agreements (FTAs), trade economists have provided ex ante computable general equilibrium (CGE) estimates to predict the trade, employment, and real per capita income effects of this agreement, such as ITC (2016). This paper-intended to complement these studies-examines the potential impacts of TPP beyond such traditional CGE estimates, taking a broader economic, governance, and historical perspective. First, we contrast these traditional CGE trade and welfare estimates that treat all firms within an industry as homogeneous with more recent CGE analyses that allow firms' productivities to be heterogeneous. We show that the latter models' trade predictions are much more consistent with ex post empirical evidence of average trade effects of FTAs. Second, empirical evidence now strongly confirms the existence of FTA "contagion." We review this evidence and show that predictive models of the evolution of FTAs indicate that the TPP should be formed. With China now having formed 12 FTAs and negotiating five new ones (including a sixteen member Asia-Pacific FTA), the United States would likely face considerable trade diversion without the TPP. Third, we examine empirical evidence on the likely further economic growth implications of FTAs by reducing firms' uncertainty over trade relations and trade policies. Fourth, we examine empirical evidence on the additional impact of FTAs on consolidating democratic institutions in countries. The TPP would likely help consolidate some of the less mature democracies. Fifth, we examine empirical evidence on the reductions of conflicts (and enhanced peace) between countries owing to the formations of FTAs. We conclude the paper noting that the potential net benefits to member countries of the proposed TPP extend well beyond the real income gains to households based upon traditional CGE models.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.154-157
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• 1999

Microwave polarimetric backscattering from a wet soil surface had been measured using a Ku-band polarimetric scatterometer at the incidence angles ranging from 10$^{\circ}$ to 70$^{\circ}$ Since the accurate target parameters as well as the radar parameters are necessary for radar scattering modeling, a complete and accurate set of ground truth data were also collected, from which accurate measurements were made of the rms height, correlation length, and dielectric constant. The measured polarimetric backscattering coefficients (vv-, hh-, vh-, hv-polarizations) were compared with theoretical models and empirical models. A new semi-empirical model for microwave polarimetric radar backscattering from bare soil surfaces was developed using polarimetric radar measurements and the knowledge based on the theoretical and numerical solutions. The model was found to yield very good agreement with the backscattering measurements of this study.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권3호
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• pp.228-234
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• 2016

Recent icebreaking ships need to be designed to enhance not only icebreaking capability but also turning ability. For the evaluation of ice resistance induced by an icebreaking hull form, HHI (Hyundai Heavy Industries) has developed the hybrid empirical formulas (Park et al., 2015) by considering the geometrical hull shape features, such as waterline and underwater sections. However, the empirical formulas have inherent limits to the precise estimation of the icebreaking and turning ability because the breaking process and the resulting pattern are ignored. For this reason, numerical calculation in time domain is performed to predict the icebreaking process and pattern. In the simulation, varying crushing stress according to velocity vectors and contact areas between hull and ice is newly introduced. Moreover, the simulation results were verified by comparing them with the model test results for three different bow-first icebreaking models.

• 한국항만경제학회지
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• 제20권1호
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• pp.1-20
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• 2004

The purpose of this paper is to analyze the degree of cargo concentration at Korean ports using Theil's Entropy and to compare the results with those of Gini coefficient, Hoyle(1983), and Hirshmann-Herfindahl models. The entropy indices were compared with other models after measuring the cargo concentration for the period of 1981-2000 among the 18 Korean ports. The core results of empirical analysis are as follows: first, the empirical results of entropy indices show the following trends: all the ports(concentration except 1996's slight deconcentration), ports in Western area(deconcentration in 1990s and slight concentration in 2000), ports in Southern area(deconcentration in 1980s and 1990s except concentration in 2000), and ports in Eastern area(continuous trends of concentration). However, competition power will be decreased if concentration is increased, because of the character of entropy index. The empirical results of 4 indices except Hoyle model show the comparatively same directions in terms of trends. This study found out the similar results among the following models: All the ports(entropy index & Gini coefficient & H-H model), ports in Western area(Entropy index &Hoyle model), ports in Southern area(Entropy index & Gini coefficient), and ports in Eastern area(Entropy index & H-H index).The policy planner of Korean ports should find out the determination factors of concentration and deconcentration of each ports and decide the investment priority, size and scope for balancing the development of regional ports.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.45-54
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• 2012

In order to predict trailing edge noise from a flat plate more effectively and accurately, the prediction algorithm based on semi-analytic model for point pressure spectrum is proposed. The semi-analytic model consists of empirical models for point pressure spectra and theoretical model to determine the boundary layer characteristics needed for the empirical models. The proposed methods are applied to predict the trailing edge noise of the flat plate located in the mean flow of speed 38 m/s, for which the measured data are available. In present study, six empirical models for point pressure spectra are utilized for the predictions of trailing edge noise and their prediction results are compared to the measured data. Through the analysis of these comparisons, it is revealed that the present method based on non-frozen formula using Efimtsov model and Smol'yakov-Tkachenko model can provide more accurate and efficient predictions of trailing edge noise.