• Journal of Labour Economics
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• v.34 no.3
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• pp.119-139
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• 2011

Using a establishment-worker matched data, this paper estimates wage differentials between standard and non-standard workers. Unlike previous studies, we estimate a fixed-effect model for the tree-way error-components that control for both unobserved individual heterogeneities and unobserved firm heterogeneities. The estimation results show that standard workers earn 6.5~8.4% mire than non-standard workers. This wage premium is 30~40% of the wage differential estimated from the OLS model. The results implies that a large proportion of the wage differentials between standard and non standard workers can be explained by unobserved firm and individual characteristics.

• Research in Community and Public Health Nursing
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• v.33 no.3
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• pp.321-331
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• 2022

Purpose: This study is to establish a structural model for standard precautions compliance of nursing students. This conceptual model was based on the IMB (Information-Motivation-Behavioral skills) model of Fisher and Fisher. Methods: Data were collected from October 12 to December 1, 2020, and the subjects were nursing students from G metropolitan city and J province, and the data of a total of 334 subjects were analyzed. For data analysis, this study used the SPSS 24.0 and AMOS 24.0 programs. Results: The hypothetical model showed a good fit to the data: 𝑥²=106.46 (p<.001), 𝑥²/df=2.54, RMSEA=.07, SRMR=.04, CFI=.96, TLI=.94. It was confirmed that the variables that have a statistically significant influence on the standard precautions compliance in nursing students were in the order of self-efficacy, social support, personal attitude, and standard precautions knowledge. The model explained 48.3% of the variance in standard precautions compliance of nursing students. Conclusion: It is necessary to develop and apply various specialized extracurricular programs that can induce an individual attitude toward observing standard precautions compliance in a positive direction in relationships with teachers and peers and gain their support.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.1
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• pp.31-42
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• 2024

In this study, the methodology of determination of base bleed motor data for base bleed projectile based on the NATO standard trajectory model, especially STANAG 4355 Method 2 were presented. Ground combustion experiments and aerodynamic performance firing tests were conducted to determine the drag reduction motor data of the base bleed projectile and this data was described based on the NATO standard ballistic model. The derived drag reduction motor data were input into the ballistic equations to complete the ballistic model and it was confirmed that the calculated predicted trajectory from the ballistic model matched well with the measured trajectory from the aerodynamic performance firing tests.

• Communications for Statistical Applications and Methods
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• v.28 no.2
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• pp.189-204
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• 2021

In a regression analysis, a single best model is usually selected among several candidate models. However, it is often useful to combine several candidate models to achieve better performance, especially, in the prediction viewpoint. Model combining methods such as stacking and Bayesian model averaging (BMA) have been suggested from the perspective of averaging candidate models. When the candidate models include a true model, it is expected that BMA generally gives better performance than stacking. On the other hand, when candidate models do not include the true model, it is known that stacking outperforms BMA. Since stacking and BMA approaches have different properties, it is difficult to determine which method is more appropriate under other situations. In particular, it is not easy to find research papers that compare stacking and BMA when regression model assumptions are violated. Therefore, in the paper, we compare the performance among model averaging methods as well as a single best model in the linear regression analysis when standard linear regression assumptions are violated. Simulations were conducted to compare model averaging methods with the linear regression when data include outliers and data do not include them. We also compared them when data include errors from a non-normal distribution. The model averaging methods were applied to the water pollution data, which have a strong multicollinearity among variables. Simulation studies showed that the stacking method tends to give better performance than BMA or standard linear regression analysis (including the stepwise selection method) in the sense of risks (see (3.1)) or prediction error (see (3.2)) when typical linear regression assumptions are violated.

• New & Renewable Energy
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• v.20 no.1
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• pp.95-101
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• 2024

Since 1990, the Renewable Big Data Research Lab at the Korea Institute of Energy Technology has been observing solar radiation at 16 sites across South Korea. Serving as the National Reference Standard Data Center for Renewable Energy since 2012, it produces essential data for the sector. By 2020, it standardized meteorological year data from 22 sites. Despite user demand for data from approximately 260 sites, equivalent to South Korea's municipalities, this need exceeds the capability of measurement-based data. In response, our team developed a method to derive solar radiation data from satellite images, covering South Korea in 400,000 grids of 500 m × 500 m each. Utilizing satellite-derived data and ERA5-Land reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), we produced standard meteorological year data for 1,000 sites. Our research also focused on data measurement traceability and uncertainty estimation, ensuring the reliability of our model data and the traceability of existing measurement-based data.

• Journal of Navigation and Port Research
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• v.36 no.2
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• pp.105-112
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• 2012

In order to improve the existing S-57 standard, International Hydrographic Organization(IHO) has developed S-100 standard, a Universal Hydrographic Data Model(UHDM) expanded from ISO 19100 series standard to hydrographic area, and is in the process of its implementation. International Maritime Organization(IMO) has established CMDS based on e-Navigation strategy data standard as International Association of Lighthouse Authorities(IALA) established IHDM based on aids to navigation data standard and each data standard is linked with the S-100 standard. Fundamental concept and core principles of S-100 standard is suitable not only for the development of a wide range of hydrographic data and service production standard, including the next generation ENC, but also the development of product specification of non-hydrographic area. This study has examined the operation principle of S-100 standard and analyzed its implementation process as e-Navigation data in relation with ENC. It also noted the utilization of S-100 standard based e-Navigation and its potential effect via examining the development cases of S-100 standard-based product specification, such as nautical publication, ship reporting and pilot request, digital routing guide, tide and water level transmission and other important data cases of e-Navigation field.

• Wind and Structures
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• v.7 no.1
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• pp.1-12
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• 2004

Numerical simulation of flow past two-dimensional hill and valley is presented. Application of three turbulence models - the standard and modified (Kato-Launder) $k-{\varepsilon}$ models and standard $k-{\omega}$ model - is discussed. The computational methodology is briefly described. The mean velocity and turbulence intensity profiles, obtained from numerical simulations of flow past the hill, are compared with the experimental data acquired in a boundary-layer wind tunnel at Colorado State University. The mean velocity, turbulence kinetic energy and Reynolds shear stress profiles from numerical simulations of flow past the valley are compared with published experimental data. Overall, the results of simulations employing the standard $k-{\varepsilon}$ model were found to be in a better agreement with the experimental data than those obtained using the modified $k-{\varepsilon}$ model and the $k-{\omega}$ model.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.534-541
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• 2005

Until now, Korean shipyards have accumulated a great amount of data. But they do not have appropriate tools to utilize the data in practical works. Engineering data contains experts' experience and know-how in its own. It is very useful to extract knowledge or information from the accumulated existing data by using data mining technique This paper treats an evolutionary computation based on genetic programming (GP), which can be one of the components to realize data mining. The paper deals with linear models of GP for the regression or approximation problem when given learning samples are not sufficient. The linear model, which is a function of unknown parameters, is built through extracting all possible base functions from the standard GP tree by utilizing the symbolic processing algorithm. In addition to a standard linear model consisting of mathematic functions, one variant form of a linear model, which can be built using low order Taylor series and can be converted into the standard form of a polynomial, is considered in this paper. The suggested model can be utilized as a designing tool to predict design parameters with small accumulated data.

• Proceedings of the CALSEC Conference
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• 1999.11a
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• pp.75-84
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• 1999

CALS is a strategy to share integrated product data through a set of standards to achieve efficiencies in business and operational mission areas. In this research, we first studied current status for CALS standard and then analyzed the case of US DoD. The results can be summarized as implementing for two major standard in defense CALS system. They are STEP and XML. Our recommendations can be used to set direction for CALS standard implementation and standard selection process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.28-33
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• 2012

The smart grid, which is an integrated type of the power system and the digital network, requires the integration of a CIM(Common Information Model) standard for information modelling at the power control centers and an IEC 61850 standard for automation at the substation level in order to efficiently exchange the information between system elements. This paper describes the method of data transfer from one standard information model to the other standard unified information model by mapping between the objects of IEC 61850 and IEC61970 CIM standards both in the static and dynamic models, and designs the method of data transfer and information exchange between the topology processing application using unified topology class packages.