• Title/Summary/Keyword: Empirical comparison

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A Semi-Empirical Correlation for an Adiabatic Interfacial Friction Factor (단열 계면 마찰계수에 대한 준 실험식)

  • Nam, Ho-Yun;Chun, Moon-Hyun
    • Nuclear Engineering and Technology
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    • v.26 no.1
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    • pp.108-118
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    • 1994
  • A semi-empirical correlation has been developed for adiabatic interfacial friction factors in a long horizontal air-water countercurrent stratified flow conditions. Using a pipe and duct test sections, a series of experiments hate been conducted varying non-dimensional water depth and flow rates of air. On the basis of simultaneous measurement of the main flow parameters in a horizontal pipe and a duct, a semi-empirical correlation for the interfacial friction factor in a stratified flow regime has been developed employing a new concept of surface roughness in wavy flow. A total of 201 data point, including 15 concurrent pipe flow test data of others, have been used in the present analysis. A comparison between the data and the predictions of the present correlation shows that the agreement is within $\pm$30%.

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Comparison of EMD and HP Filter for Cycle Extraction with Korean Macroeconomic Indices (순환성분 추출을 위한 EMD와 HP 필터의 비교분석: 한국의 거시 경제 지표에의 응용)

  • Park, Minjeong;Seong, Byeongchan
    • The Korean Journal of Applied Statistics
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    • v.27 no.3
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    • pp.431-444
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    • 2014
  • We introduce the empirical model decomposition (EMD) to decompose a time series into a set of components in the time-frequency domain. By using EMD, we also extract cycle and trend components from major Korean macroeconomic indices and forecast the indices with the components combined. In order to evaluate their efficiencies, we investigate volatility, autocorrelation, persistence, Granger causality, nonstationarity, and forecasting performance. They are then compared with those by Hodrick-Prescott filter which is the most commonly used method.

Truncated Kernel Projection Machine for Link Prediction

  • Huang, Liang;Li, Ruixuan;Chen, Hong
    • Journal of Computing Science and Engineering
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    • v.10 no.2
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    • pp.58-67
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    • 2016
  • With the large amount of complex network data that is increasingly available on the Web, link prediction has become a popular data-mining research field. The focus of this paper is on a link-prediction task that can be formulated as a binary classification problem in complex networks. To solve this link-prediction problem, a sparse-classification algorithm called "Truncated Kernel Projection Machine" that is based on empirical-feature selection is proposed. The proposed algorithm is a novel way to achieve a realization of sparse empirical-feature-based learning that is different from those of the regularized kernel-projection machines. The algorithm is more appealing than those of the previous outstanding learning machines since it can be computed efficiently, and it is also implemented easily and stably during the link-prediction task. The algorithm is applied here for link-prediction tasks in different complex networks, and an investigation of several classification algorithms was performed for comparison. The experimental results show that the proposed algorithm outperformed the compared algorithms in several key indices with a smaller number of test errors and greater stability.

Function of Fund Distributor and Appropriateness of Sales Fees in Funds (펀드 판매사의 역할과 판매 보수의 적정성 : 한국의 주식형 펀드를 대상으로)

  • Won, Seung-Yeon
    • The Korean Journal of Financial Management
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    • v.26 no.1
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    • pp.31-64
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    • 2009
  • This paper evaluates the role of fund distributors and the appropriateness of sales fees in funds by the empirical analysis of Korean equity funds. The empirical results are summarized as follows. First, this paper shows that the funds with higher sales fees do not have better performance. Rather, the higher sales fees cause the returns of funds to decrease in Korean equity funds. Second, it is not confirmed that both banks and securities firms, as fund distributors, contribute to the better performance of funds. Especially, the banks gave more negative influence on the performance of funds by imposing higher sales fees in funds than the securities firms. The empirical results suggest that the sales fees of funds are unduly imposed in comparison to the function of fund distributors and therefore, the structure of fund fees should be improved for the benefit of fund investors.

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Development of Mass Transfer Models for Ammonia Flux Estimation from Sewage Treatment Plants (하수처리장에서의 암모니아 플럭스 산정을 위한 물질전달모형 개발)

  • Sa, Jae-Hwan;Jeon, Eui-Chan;Jeong, Jae-Hak
    • Journal of Korean Society for Atmospheric Environment
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    • v.22 no.5
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    • pp.701-711
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    • 2006
  • Sewage treatment plants located near to large cities emit extremely higher concentration of odorous materials. This study evaluated flux profiles of ammonia emitted from the water surface of sewage treatment plants using a dynamic flux chamber. Also, an ammonia overall mass transfer coefficient and a mass transfer model was developed in order to estimate fluxes of ammonia using environment parameters and the flux from the sewage treatment plants. The developed mass transfer model was evaluated through a fitness analysis. Comparison modeled flux applying empirical overall mass transfer coefficients of ammonia and measured ammonia flux show a high linearity with 0.977. The flux ratio of 1.282 demonstrated highly statistical fitness, also. Modeled flux using the mass transfer model was compared with measured flux. In result, it indicated that empirical overall mass transfer coefficients were similar to measured flux. The mass transfer model using the empirical overall mass transfer coefficient developed in this study was proved to be an easy and effective method to make accurate and precise predictions for ammonia flux discharged from sewage treatment plants.

A Comparison Study on Compression Index of Marine Clay with High-Plasticity (고소성 해성점토지반의 압축지수에 대한 비교 연구)

  • Jung, Gil-Soo;Park, Byung-Soo;Hong, Young-Kil;Yoo, Nam-Jae
    • Journal of Industrial Technology
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    • v.25 no.A
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    • pp.57-65
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    • 2005
  • In this paper, for the highly plastic marine soft clay distributed in west and southern coast of Korean peninsula of Kwangyang and Busan New Port areas, correlation between compression index and other indices representing geotechnical engineering properties such as liquid limit, void ratio and natural water content were analyzed. Appropriate empirical equations of being able to estimate the compressibility of clays in the specific areas were proposed and compared with other existing empirical ones. For analyses of the data and test results, data for marine clays were used from areas of the South Container Port of the Busan New Port, East Breakwater, Passenger Quay, Jungma Reclamation and Reclamation Containment in the 3rd stage in Kwangyang. In order to find the best regression model by using the commercially available software, MS EXCEL 2000, results obtained from the simple linear regression analysis, using the values of liquid limit, initial void ratio and natural water content as independent variables, were compared with the existing empirical equations. Multiple linear regression was also performed to find the best fit regression curves for compression index and other soil properties by combining those independent variables. On the other hands, another software of SPSS for non-linear regression was used to analyze the correlations between compression index and other soil properties.

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Dynamic Constitutive Equations of Auto-body Steel Sheets with the Variation of Temperature (II) - Flow Stress Constitutive Equation - (차체용 강판의 온도에 따른 동적 구성방정식에 관한 연구 (II) - 온도에 따른 동적 구성방정식 -)

  • Lee, Hee-Jong;Song, Jung-Han;Park, Sung-Ho;Huh, Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.2 s.257
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    • pp.182-189
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    • 2007
  • This paper is concerned with the empirical flow stress constitutive equation of steel sheets for an auto-body with the variation of temperature and strain rate. In order to represent the strain rate and temperature dependent behavior of the flow stress at the intermediate strain rates accurately, an empirical hardening equation is suggested by modifying the well-known Khan-Huang-Liang model. The temperature and strain rate dependent sensitivity of the flow stress at the intermediate strain rate is considered in the hardening equation by coupling the strain, the strain rate and the temperature. The hardening equation suggested gives good correlation with experimental results at various intermediate strain rates and temperatures. In order to verify the effectiveness and accuracy of the suggested model quantitatively, the standard deviation of the fitted result from the experimental one is compared with those of the other two well-known empirical constitutive models such as the Johnson-Cook and the Khan-Huang-Liang models. The comparison demonstrates that the suggested model gives relatively well description of experimental results at various strain rates and temperatures.

A Study on Management System for Improving of Equipment Productivity in Injection Machining Process (사출가공공정에서 설비생산성 향상을 위한 관리체계에 대한 연구)

  • Park, Jun-Byung;Bae, Young-Ju
    • Journal of the Korea Safety Management & Science
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    • v.19 no.1
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    • pp.219-226
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    • 2017
  • This study investigates application cases of facility management system model for enhancing facility productivity of industry filed around medium and small facility processing companies and finds the inefficiency of the existing management model. Following items are researched to seek out methods and measures to maximize facility productivity through empirical analysis by exploring and establishing a new management model. First, the empirical analysis, it is found that the overall equipment efficiency index used for facility productivity management in the companies has a difficulty being used as the index for it in actual medium-small processing companies. Second, a new facility management system model applying standard cycle time is suggested among facility management index system to measure facility productivity. Third, the empirical analysis is used to verify that developed facility management system model is a useful method to manage the facility productivity by applying the model to actual medium-small processing companies. Finally, it is necessary to implement comparison analysis on whether actual productivity enhancement induces a distinctly different result by using a new facility management index system model to be inhibited in this study.

Single Line-to-ground Fault Location and Information Modeling Based on the Interaction between Intelligent Distribution Equipment

  • Wang, Lei;Luo, Wei;Weng, Liangjie;Hu, Yongbo;Li, Bing
    • Journal of Electrical Engineering and Technology
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    • v.13 no.5
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    • pp.1807-1813
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    • 2018
  • In this paper, the fault line selection and location problems of single line-to-ground (SLG) fault in distribution network are addressed. Firstly, the adaptive filtering property for empirical mode decomposition is formulated. Then in view of the different characteristics showed by the intrinsic mode functions(IMF) under different fault inception angles obtained by empirical mode decomposition, the sign of peak value about the low-frequency IMF and the capacitance transient energy is chosen as the fault line selection criteria according to the different proportion occupied by the low-frequency components. Finally, the fault location is determined based upon the comparison result with adjacent fault passage indicators' (FPI) waveform on the strength of the interaction between the distribution terminal unit(DTU) and the FPI. Moreover, the logic nodes regarding to fault line selection and location are newly expanded according to IEC61850, which also provides reference to acquaint the DTU or FPI's function and monitoring. The simulation results validate the effectiveness of the proposed fault line selection and location methods.

Shear strength model for reinforced concrete beam-column joints based on hybrid approach

  • Parate, Kanak N.;Kumar, Ratnesh
    • Computers and Concrete
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    • v.23 no.6
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    • pp.377-398
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    • 2019
  • Behavior of RC beam-column joint is very complex as the composite material behaves differently in elastic and inelastic range. The approaches generally used for predicting joint shear strength are either based on theoretical, strut-and-tie or empirical methods. These approaches are incapable of predicting the accurate response of the joint for entire range of loading. In the present study a new generalized RC beam-column joint shear strength model based on hybrid approach i.e. combined strut-and-tie and empirical approach has been proposed. The contribution of governing parameters affecting the joint shear strength under compression has been derived from compressive strut approach whereas; the governing parameters active under tension has been extracted from empirical approach. The proposed model is applicable for various conditions such as, joints reinforced either with or without shear reinforcement, joints with wide beam or wide column, joints with transverse beams and slab, joints reinforced with X-bars, different anchorage of beam bar, and column subjected to various axial loading conditions. The joint shear strength prediction of the proposed model has been compared with 435 experimental results and with eleven popular models from literature. In comparison to other eleven models the prediction of the proposed model is found closest to the experimental results. Moreover, from statistical analysis of the results, the proposed model has the least coefficient of variation. The proposed model is simple in application and can be effectively used by designers.