• Ocean and Polar Research
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• v.23 no.3
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• pp.223-242
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• 2001

This paper presents the depth-mean monthly variation in the circulation of the Yellow Sea and the East China Sea computed using a robust diagnostic model. The mixed three-dimensional finite-difference Galerkin function model developed by Lee et at. (2000, 2001) has been extended to take into account baroclinic effects and then used to calculate the depth-mean flow fields as part of the results. In addition to M2 tide and oceanic flows previously considered, the model has been driven by the monthly mean wind stresses from Na and Seo (1998), the density gradient calculated based on by GDEM data set released by US Navy. Model results are very encouraging in that many of observed features including Jeju Cyclonic Gyre and frontal eddies along the shelfside of the Kuroshio main stream and west of Kyushu, are satisfactorily reproduced and are expected to be of value in interpreting observations in various oceanograhic disciplines.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.800-806
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• 2018

Software efficiency is the probability of failure free use in operating environments, and is the most fundamental factor affecting software system stability. The malfunction of the computer system used in the information technology field may cause a significant loss in the related industry. Therefore, in this study, we analyze the attributes of software reliability models that depend on various hazard functions based on finite fault NHPP model with software failure time data. The hazard function pattern of proposed model is constant for the Goel-Okumoto model, and the Minimax and Rayleigh models follow the incremental pattern, but the hazard function increase value of the Minimax model is smaller than that of the Rayleigh model and the Goel-Okumoto model. Also, the Minimax model was relatively efficient because the true value error of the mean value function m(t) and the mean square error (MSE) of the Minimax model were smaller than those of the Rayleigh and Goel-Okumoto models. The results of this study are expected to be useful for software developers as basic information about the hazard function.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.1
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• pp.111-120
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• 2018

The purpose of this study was to develop a ridge regression (RR) model to estimate BOD and TP load using runoff weighted value. The concept of runoff weighted value, based on distributed curve-number (CN), was introduced to reflect the impact of land covers on runoff. The estimated runoff depths by distributed CN were closer to the observed values than those by area weighted mean CN. The RR is a technique used when the data suffers from multicollinearity. The RR model was developed for five flow duration intervals with the independent variables of daily runoff discharge of seven land covers and dependent variables of daily pollutant load. The RR model was applied to Heuk river watershed, a subwatershed of the Han river watershed. The variance inflation factors of the RR model decreased to the value less than 10. The RR model showed a good performance with Nash-Sutcliffe efficiency (NSE) of 0.73 and 0.87, and Pearson correlation coefficient of 0.88 and 0.93 for BOD and TP, respectively. The results suggest that the methods used in the study can be applied to estimate pollutant load of different land cover watersheds using limited data.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.5 s.118
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• pp.84-99
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• 2006

The traditional temples located in national parks have various functions, such as religious practice, tourist destination, and conservation for cultural and natural resources. One functions have implicit monetary values in terms of public benefits. The purpose of this study was to estimate both use and non-use conservation values for two traditional temples, Sinheungsa and Haeinsa, using the contingent valuation method. In the study, both single-bounded and double-bounded dichotomous choice methods were used in an application of Turnbull distribution-free model. A total of 659 visitors were interviewed, 350 in Sinheungsa and 309 in Haeinsa. The mean WTP (willingness to pay) for Sinheungsa using single-bounded method was 4,040 Won for the use value, 6,157 Won for the cultural conservation value, and 5,624 Won for the natural conservation value. The mean WTP for Haeinsa using single-bounded method was 6,463 Won for the use value, 8,769 Won for the cultural conservation value, and 8,013 Won for the natural conservation value. The total economic value of each temple accounted for 50% (Sinheungsa) and 80% (Haeinsa) of the total economic value of the associated national park. It was also found that the single-bounded method was more conservative than the double-bounded method in terms of value estimation. The WTP was highest for the cultural conservation value and lowest for the use values in both temples, with natural conservation values falling in the middle, which showed that people perceived traditional temples as the cultural heritage. Based on these results, it was suggested that traditional temples should be designated as an 'multiple heritage area' so that conservation can be used as the main criteria for various use programs.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.3
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• pp.145-153
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• 2015

This study aims to accurately estimate population distribution more specifically than administrative unites using a RK (Regression-Kriging) model. The RK model is the areal interpolation technique that involves linear regression and the Kriging model. In order to estimate a population’s distribution using a sample region, four different models were used, namely; a regression model, RK model, OK (Ordinary Kriging) model and CK (Co-Kriging) model. The results were then compared with each other. Evaluation of the accuracy and validity of evaluation analysis results were the basis RMSE (Root Mean Square Error), MAE (Mean Absolute Error), G statistic and correlation coefficient (ρ). In the sample regions, every statistic value of the RK model showed better results than other models. The results of this comparative study will be useful to estimate a population distribution of the metropolitan areas with high population density

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.101-108
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• 2016

The RCS characteristics of stealth modified three-surface aircraft are analyzed in this paper. Prototype A is built with CATIA software and the three-dimensional digital models of modified stealth three-surface B and C are also designed based on carrier-based aircraft Su-33; the numerical simulation of RCS characteristics of three-surface aircraft is conducted with RCSAnsys software based on physical optics method and the method of equivalent currents; The following results are obtained by comparative analysis and mathematical statistics: (1) by the use of physical optics method and equivalent electromagnetic current method, the scattering intensity for each part of the model and RCS characteristic of the aircraft can be analyzed efficiently and accurately; (2) compared with model A, the mean RCS value of model B is reduced to 14.1% in forward direction and 48.1% in lateral direction; (3) compared with model A, the mean RCS value of model C decreases to 11.4% in forward direction and 21.6% in lateral direction. The results are expected to provide theoretical basis and technical support to the conceptual design of aircraft and stealth technology research.

• Communications for Statistical Applications and Methods
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• v.16 no.1
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• pp.127-135
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• 2009

It is necessary to forecast the amount of the maximum electricity demand for stabilizing the flow of electricity. The time series data was collected from the Korea Energy Research between January 2000 and December 2006. The data showed that they had a strong linear trend and seasonal change. Winters seasonal model, ARMA model were used to examine it. Root mean squared prediction error and mean absolute percentage prediction error were a criteria to select the best model. In addition, a nonstationary generalized extreme value distribution with explanatory variables was fitted to forecast the maximum electricity.

• Nuclear Engineering and Technology
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• v.46 no.5
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• pp.619-632
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• 2014

The Best Estimate Plus Uncertainty (BEPU) method has been widely used to evaluate the uncertainty of a best-estimate thermal hydraulic system code against a figure of merit. This uncertainty is typically evaluated based on the physical model's uncertainties determined by expert judgment. This paper introduces the application of data assimilation methodology to determine the uncertainty bands of the physical models, e.g., the mean value and standard deviation of the parameters, based upon the statistical approach rather than expert judgment. Data assimilation suggests a mathematical methodology for the best estimate bias and the uncertainties of the physical models which optimize the system response following the calibration of model parameters and responses. The mathematical approaches include deterministic and probabilistic methods of data assimilation to solve both linear and nonlinear problems with the a posteriori distribution of parameters derived based on Bayes' theorem. The inverse problem was solved analytically to obtain the mean value and standard deviation of the parameters assuming Gaussian distributions for the parameters and responses, and a sampling method was utilized to illustrate the non-Gaussian a posteriori distributions of parameters. SPACE is used to demonstrate the data assimilation method by determining the bias and the uncertainty bands of the physical models employing Bennett's heated tube test data and Becker's post critical heat flux experimental data. Based on the results of the data assimilation process, the major sources of the modeling uncertainties were identified for further model development.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.755-762
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• 2013

In this paper we consider the NHPP software reliability model. And we deal with the maximum likelihood estimation and the Bayesian estimation with conjugate prior for parameter inference in the mean value function of Goel-Okumoto model (1979). The parameter estimates for the proposed model is presented by MLE and Bayes estimator in data set. We compare the predicted number of faults with the actual data set using the proposed mean value function.

• The Korean Journal of Ecology
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• v.2 no.1
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• pp.1-8
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• 1978

Epiphytic lichens were sampled quantitatively on the cherry trees (Prunus serrulata) at Jeonju and Hadong along both north and south exposures of tat trees. Coverage of lichens was determinated for each species by 10*20cm quadrat. Lichen species diversities such as total diversity (D), mean diversity (D), Shannon diversity (D') and redundancy (R) were estimated according to Brillouin and Shannon equation. The importance value of lichen species was meassured by niche preemption model, The importance value transformed into some fraction k of the niche space. The value of k was compared with aggregation of lichens communities in to areas. The ten most important awariensis, Parmelia incurva, Parmelia crinita, Dirinaria applanta, Parmelia wallichiana, Parmelia austrosinensis and Cetraria platyphylla. The mean coverage epiphytic lichens on north side of tree was higher than of south side in two areas. The species diversities of epiphytic lichen of two areas shows that a change in the value of D' along vertical was not paralled with the D and R. In Kumsan-sa, D, D and D' increased upward along the tree of north exposure, but did not follow this trend in south, However in Sangge-sa, D, D and D' of both sides increased.