• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.703-710
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• 2012

At the stage of conceptual design of a helicopter, it is a general way using low fidelity analysis methods because of a large number of design calculations and trade-off studies. Determination of empirical parameters used in analysis codes for more practical design, depends on an user's design experiences, which effects on the accuracy and the fidelity of conceptual design results. Thus, more precise and logical method should be required to determine the empirical parameters used in the conceptual design of a helicopter. The present method is to be used not only in verifying the empirical parameters generated by design requirements, but also regenerate them if they contain any errors. Empirical parameters produced by present method were used to design a helicopter with a payload objective and performance constraints of an operating helicopter. As a result, weights and geometries of designed helicopter matched the target value within 5% significance level, proving that the suggested parameter generating method can be useful in the conceptual design of a helicopter.

• Geomechanics and Engineering
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• v.30 no.1
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• pp.11-26
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• 2022

One of the most important issues in tunneling, is the squeezing phenomenon. Squeezing can occur during excavation or after the construction of tunnels, which in both cases could lead to significant damages. Therefore, it is important to predict the squeezing and consider it in the early design stage of tunnel construction. Different empirical, semi-empirical and theoretical-analytical methods have been presented to determine the squeezing. Therefore, it is necessary to examine the ability of each of these methods and identify the best method among them. In this study, squeezing in a part of the Alborz service tunnel in Iran was estimated through a number of empirical, semi- empirical and theoretical-analytical methods. Among these methods, the most robust model was used to obtain a database including 300 data for training and 33 data for testing in order to develop a machine learning (ML) method. To this end, three ML models of Gaussian process regression (GPR), artificial neural network (ANN) and support vector regression (SVR) were trained and tested to propose a robust model to predict the squeezing phenomenon. A comparative analysis between the conventional and the ML methods utilized in this study showed that, the GPR model is the most robust model in the prediction of squeezing phenomenon. The sensitivity analysis of the input parameters using the mutual information test (MIT) method showed that, the most sensitive parameter on the squeezing phenomenon is the tangential strain (ε_θ^α) parameter with a sensitivity score of 2.18. Finally, the GPR model was recommended to predict the squeezing phenomenon in tunneling projects. This work's significance is that it can provide a good estimation of the squeezing phenomenon in tunneling projects, based on which geotechnical engineers can take the necessary actions to deal with it in the pre-construction designs.

• Journal of the Korean Data and Information Science Society
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• v.17 no.2
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• pp.279-289
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• 2006

This paper concerns with the effects of the specialized projected for the local W university on education which was planned and conducted in October 2004. From the empirical study using the correlation analysis, regression analysis, and structured equation model, we found some results that educational service satisfaction was highly correlated with general instruction factor and hard ware factor less correlated. Also we investigated that university educational service satisfaction was deeply correlated with word of mouth.

• Tunnel and Underground Space
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• v.6 no.3
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• pp.234-238
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• 1996

Three empirical criteria of rock failure are analyzed in order to understand the meaning of coefficients. Transformation of equations is discussed to apply in the numerical analysis. New failure criterion for intact rocks is proposed in this study, which can be used directly in programming. New equation has the form of parabolic curve($\alpha$=0.5~1.0), and is based on Mohr's shear failure using data from triaxial tests. Its validity will be discussed in the next report.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.54
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• pp.119-128
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• 2000

This study develops the pay satisfaction questionnaire for Korean employees. Based upon the review of previous studies, 16 questionnaire items are developed. Exploratory factor analysis results in a modified measurement through item deletion, item-to-dimension reassignment, and dimension combination. The measurement model was good fit assessed by overall fit measures(GFI; goodness of fit index, AGFI; adjusted goodness of fit index, RMR; root mean square residual) criteria, lambda score, and squared multiple correlation with confirmatory factor analysis. Implication of this work for future theoretical and empirical development are suggested.

• Journal of Korea Port Economic Association
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• v.33 no.3
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• pp.69-90
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• 2017

Areas of marine activity have expanded into exclusive economic zones and the continental shelf since the United Nations Convention on the Law of the Sea(UNCLOS) in 1994, The signatory countries have been enforcing their maritime rights and competition in the international community has become intensified. Marine-related issues, including maritime sovereignty, has become an increasingly important issue with many national security and related studies following this trend. However, while there are many policy-related studies there remain few empirical studies. This paper conducted a study of illegal cases of Chinese fishing boats which are quite frequently for an empirical study on maritime sovereignty. This study conducted empirical analysis regarding factors relating to ocean sovereignty infringement by using correlation and multiple regression analysis. The result of observed increases in illegal Chinese fishing boats decreased the production of aquatic products, whish resulted in economic fishery losses to Korea households and inflation in the Korean economy.

• Journal of the Korean Society of Costume
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• v.65 no.1
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• pp.30-45
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• 2015

This study summarizes the dissemination aspects of liturgical vestments in Korea, and organizes the value and meanings of these disseminations as it appeared in the history of costumes by carrying out an empirical analysis on the relics of liturgical vestments since the modern times. It also examines its design characteristics as well. Liturgical vestments have symbolic meaning for the purpose and solar term of ceremonial occasions and it also functions as a way to differentiate the position and duty of the clergy. Liturgical vestments developed on the basis of ancient Greek-Roman costumes and transformed each situation and social trend of the age. Korean liturgical vestments started with their traditional costumes, in 1887, it were changed into French(western) style with freedom of religious. After the secondary Vatican Council held in 1962, various regulations were changed to spread the Catholic doctrines and ideology. This study conducted an empirical analysis and design consideration on the 28 relics of modern liturgical vestments on the basis of the foregoing standard and concept. As a result of analysis, relics were investigated as research materials worn by Bishops after 1960s. And design elements are that the relics used materials and ornament of Hanbok with flower patterns and decoration such as letter patterns including 壽(life) 福(luck) 喜(pleasure) as well as Chrysanthemum and Mancaowen design. These transition reflected by amend regulation of Vatican Council II. Accordingly, this data has been confirmed to be important for the history of costumes as it informs what process of changes liturgical vestments spread in Korea went through before they are worn as current appearance.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.244-252
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• 2014

EOF (Empirical Orthogonal Function) analysis is applied to investigate the sand movement in Hujeong Beach. For the analysis, the profile data which were observed five times from June 2009 to May 2010 along the 13 baselines were used. To secure the temporal and physical consistency among the 13 profile data, the 13 profile data were combined into one data and using this data the EOF analysis was performed. According to the analysis, the first EOF is related with the mean topography and the second EOF represents the natural variation of sediment migration and the third EOF is related with the along-shore sediment transport arising from storm. The remaining EOFs show no special relation with wave conditions. In conclusion the main factors which are having great effects on Hujeong Beach's sand movement are analyzed as natural variation and along-shore sediment transport owing the wave conditions.

• Journal of Digital Convergence
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• v.14 no.7
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• pp.497-506
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• 2016

The purpose of this study is to inquire into the relationships between empirical value, emotional response and behavioral response of skin-SCUBA diving participants. This study sampled 300 skin-SCUBA diving participants in the SCUBA diving pool of the Seoul Olympic Stadium, and the SCUBA diving pool of the Suwon World Cup Stadium by using convenience sampling. For data processing, this study conducted frequency analysis, exploratory factor analysis, reliability analysis, correlation analysis and multi-regression analysis using PASW 18.0 Ver. The concrete results are as follows: First, the empirical value of a skin-SCUBA diving participant was found to have a significant influence on emotional responses. Second, the empirical value of a skin-SCUBA diving participant was found to have a significant influence on behavioral responses. Third, the emotional response of a skin-SCUBA diving participant was found to have a significant influence on behavioral responses.

• Fire Science and Engineering
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• v.17 no.2
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• pp.43-49
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• 2003

For the inert gases of Ar, $N_2$and $CO_2$, the empirical equations of the gas mixture were correlated in terms of saturated pressure, density and viscosity. They were obtained by regression analysis based on the mixing rule. The empirical equation of saturated pressure was assumed as the first order function of temperature. The empirical form of density was expressed as compressibility factor and saturated pressure while the empirical equation of viscosity was formulated as a power function of temperature. This empirical equations of the physical properties were obtained in the composition of Ar, $N_2$and $CO_2$, 40/50/10(mol. %).