• Atmosphere
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• v.26 no.1
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• pp.85-95
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• 2016

In this study, we investigated the variabilities of wind speed of 850 hPa and precipitable water over the East Asia region using the NCEP Final Analysis data from December 2001 to November 2011. A large variance of wind speed was observed in northern and eastern China during the winter period. During summer, the regions of the East China Sea, the South Sea of Japan and the East Sea show large variances in the wind speed caused by an extended North Pacific High and typhoon activities. The large variances in the wind speed in the regions are shown to be correlated with the inter-annual variability of precipitable water over the inland region of windward side of the Korean Peninsula. Based on the investigation, sensitivity tests to the domain size were performed using the WRF model version 3.6 for heavy precipitation events over the Korean Peninsula for 26 and 27 July 2011. Numerical experiments of different domain sizes were set up with 5 km horizontal and 50 levels vertical resolutions for the control and the first experimental run, and 9 km horizontal for the second experimental run. We found that the major rainfalls correspond to shortwave troughs with baroclinic structure over Northeast China and extended North Pacific High. The correlation analysis between the observation and experiments for 1-h precipitation indicated that the second experiment with the largest domain had the best performance with the correlation coefficient of 0.79 due to the synoptic-scale systems such as short-wave troughs and North Pacific High.

• Korean Journal of Child Studies
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• v.28 no.1
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• pp.115-128
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• 2007

Participants in this study to develop the Korean version of the Early Childhood Home Observation for Measurement of the Environment(EC-HOME) were 294 3- to 6- year-old children enrolled in a child care center and their parents. Results were that EC-HOME had sufficient internal reliability : Cronbach's ${\alpha}=.80$. Correlation of test-retest ranged from .76~.97. In item-analysis, 9 items with low 'corrected item-total correlation' were removed resulting in 30 items. Factor analysis confirmed 6 factors : 1) Learning Material, 2) Learning Stimulation, 3) Responsivity, 4) Physical Environment, 5) Language Stimulation, and 6) Variety of Materials. Analysis of the relation of children's home environment to their characteristic variances with parents and developmental functioning showed high internal consistency and convergent validity of the sub-scales.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.118-127
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• 2017

The aim of the present study is to research how the main factors for the export of SMEs affect SME's Export possibility in structural method. 62 SMEs in Busan Region were participated in this study. For the empirical analysis, a multiple regression analysis and a path analysis were used with Spss18 and Amos 5v to figure out the relationship between the main factors and SME's Export possibility(SEP). The main factors as variances are "Manpower Needs(MN)", "Technology Innovation Needs(TIN)", "Education Needs for Export(ENE)" and "Intention of Decision-Maker(IDM)". The result indicated that ENE and TIN with IDM could structurally affect SEP through path analysis and implies that the main factors have to be considered with the intention of decision-maker as CEO for the successful export of SMEs.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.43-52
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• 2010

In this study, the shapes of the wheel and rail are represented by using 3-dimensional surface functions with surface parameters and a 3-dimensional wheel-rail contact analysis is presented. A whole numerical solution of wheel-rail contact at tread and flange including 2-point contacts can be achieved with the proposed numerical algorithm. Kinematic characteristics such as variances of vertical displacement and roll angle, and variance of wheel radius difference for arbitrary yaw and lateral displacement of wheelset, are determined for the KTX wheel-rail pair as an example. The condition of yaw and lateral displacement occurring 2-point contacts to analyze derailment are compared between standard and worn wheels. Differences of contact characteristics between curved and straight rails are also analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.971-977
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• 2005

Power Flow Analysis (PFA) is developed for the effective predictions of frequency-averaged vibrational response in medium-to-high frequency ranges. In PFA, the power coefficients of semi-infinite structure and for-field energy density are used to predict the vibrational responses of structures. Generally, at high frequencies, PFA can predict narrow-band frequency-averaged vibrational responses of built-up structures. However, in low- to medium frequency ranges, the dynamic responses obtained by PFA represent broad-band frequency-averaged vibrational energy densities. For the prediction of vibrational response variance in Power Flow Finite Element Method (PFFEM), the variances of input power and joint element matrix describing structural coupling relationship are derived. Finally, for the validity of developed formulation, numerical examples for two co-planer plates are performed and the vibrational response variance of the structure are compared with the results of classical and PFFEM solutions.

• Journal of the Korean Data and Information Science Society
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• v.17 no.3
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• pp.919-925
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• 2006

Maximum likelihood estimate(MLE) is obtained from the partial log-likelihood function for the cell probabilities of two way incomplete contingency tables proposed by Chen and Fienberg(1974). The partial log-likelihood function is modified by adding lagrangian multiplier that constraints can be incorporated with. Variances of MLE estimators of population proportions are derived from the matrix of second derivatives of the loglikelihood with respect to cell probabilities. Simulation results, when data are missing at random, reveal that Complete-case(CC) analysis produces biased estimates of joint probabilities under MAR and less efficient than either MLE or MI. MLE and MI provides consistent results under either the MAR situation. MLE provides more efficient estimates of population proportions than either multiple imputation(MI) based on data augmentation or complete case analysis. The standard errors of MLE from the proposed method using lagrangian multiplier are valid and have less variation than the standard errors from MI and CC.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.695-699
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• 2005

Propriety of PERT network for planning and management in large-scale systems was investigated. We also review the example of small and middle size system to compare the appropriateness of PERT analysis method. For comparing the appropriateness of PERT analysis method the calculation time, and the variances were estimated. Eventualy, we proposed the criteria of PERT analysis method for planning and management large-scale systems.

• Journal of the Korean Data and Information Science Society
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• v.15 no.4
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• pp.993-1002
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• 2004

Imputation procedures such as fully efficient fractional imputation(FEFI) or multiple imputation(MI) can be used to construct complete contingency tables from samples with partially classified responses. Variances of FEFI estimators of population proportions are derived. Simulation results, when data are missing completely at random, reveal that FEFI provides more efficient estimates of population than either multiple imputation(MI) based on data augmentation or complete case analysis, but neither FEFI nor MI provides an improvement over complete-case(CC) analysis with respect to accuracy of estimation of some parameters for association between two variables like $\theta_{i+}\theta_{+i}-\theta_{ij}$ and log odds-ratio.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3166-3181
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• 2012

Localization of mobile station (MS) has now gained considerable attention. Since the hybrid measurements can help to improve the positioning accuracy, several hybrid localization methods have been proposed in the literature. However, the high performance estimator with the closed-form solution and complete performance analysis for time-of-arrival/signal strength (TOA/SS) localization technique is still an opening issue. Two TOA/SS localization algorithms with the closed-form solutions are proposed for the cases with or without uncertainty in the positions of base stations. Furthermore, performance analysis for the TOA/SS localization technique is presented. Both the theoretical variances and Cramer-Rao lower bounds (CRLBs) are derived and the relationship between the cases with or without uncertainty is given. The paper also proves that the TOA/SS scheme has a lower CRLB than the TOA (or SS) scheme. Theoretical analysis and simulations show that the proposed method can reach its CRLB.

• Journal of KIISE:Software and Applications
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• v.37 no.1
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• pp.1-8
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• 2010

Recently lots of attention has been paid to gene set analysis for identifying differentially expressed gene-sets between two sample groups. Unlike earlier approaches, the gene set analysis enables us to find significant gene-sets along with their functional characteristics. For this reason, various novel approaches have been suggested lately for gene set analysis. As one of such, PAGE is a parametric approach that employs average difference (AD) as an expression metric to quantify expression differences between two sample groups and assumes that the distribution of gene scores is normal. This approach is preferred to non-parametric approach because of more effective performance. However, the metric AD does not reflect either gene expression intensities or variances over samples in calculating gene scores. Thus, in this paper, we investigate the usefulness of several other expression metrics for parametric gene-set analysis, which consider actual expression intensities of genes or their expression variances over samples. For this purpose, we examined three expression metrics, WAD (weighted average difference), FC (Fisher's criterion), and Abs_SNR (Absolute value of signal-to-noise ratio) for parametric gene set analysis and evaluated their experimental results.