• Journal of Positioning, Navigation, and Timing
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• v.13 no.1
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• pp.63-73
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• 2024

NeQuick G is the ionosphere model utilized by Galileo single-frequency users to estimate the ionospheric delay on each user-satellite link. The model is characterized by the effective ionization level (Az) index, determined by a modified dip latitude (MODIP) and broadcast coefficients derived from daily global space weather observations. However, globally fitted Az coefficients may not accurately represent ionosphere within local area. This study introduces a method for regional ionospheric modeling that searches for locally optimized Az coefficients. This approach involves fitting TEC output from NeQuick G to TEC data collected from GNSS stations around Korea under various ionospheric conditions including different seasons and both low and high solar activity phases. The optimized Az coefficients enable calculation of the Az index at any position within a region of interest, accounting for the spatial variability of the Az index in a polynomial function of MODIP. The results reveal reduced TEC estimation errors, particularly during high solar activity, with a maximum reduction in the RMS error by 85.95%. This indicates that the proposed method for NeQuick G can effectively model various ionospheric conditions in local areas, offering potential applications in GNSS performance analyses for local areas by generating various ionospheric scenarios.

• Journal of the Korean Society for Railway
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• v.2 no.3
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• pp.46-53
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• 1999

In this paper, made was a study on a mesh generation method based on the pollution error. This method is designed for the control of the pollution error in any patch of elements of interest. It is a well-known fact that the pollution error estimates are much more than the local one. When the pollution error is significant, nothing can be said about the reliability of any estimator based on local computations in the patch. Reliable a posteriori error estimation is possible by controlling the pollution error in the patch through proper design of the mesh outside the patch. This design is possible by equally distributing the pollution error indicators over the mesh outside the patch. The mesh generated from the conventional feedback pollution-adaptive mesh generation algorithm needs many iterations. Therefore, the solution time is significant. But the remeshing scheme in the proposed method was used here. It was shown that the pollution-adaptive mesh improves the E.I., simply denoted as Effectivity Index, on the patch of interest, and the pollution error reduces less than the local error.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.308-315
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• 2002

Fragility analysis is widely used for the seismic safety evaluation of a structure. In fragility analysis, damage evaluation is a crucial factor. Most of the present fragility analyses use the representative responses such as displacement and absorbed hysteretic energy as a tool of damage evaluation. But damage evaluation method that can represent the local damage of a structure is required in the case of piers of which the local damage can cause the whole failure of bridge system. Therefore this study proposes a damage index, which can represent the distribution and magnitude of local damage by using the Lee and Fenves'plastic-damage model. Using the proposed damage index, fragility curves and damage probability matrix of pier are produced and fragility analysis is performed.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.333-336
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• 2002

This paper presents a new image segmentation method using fuzzy measures which reflect the local property of an image as well as the global property of an image An image is globally segmented into the crisp region and the ambiguous region in terms of the Index of fuzziness measured over all pixels of an image. The ambiguous region is luther partitioned into background and object in terms of the index of fuzziness computed over the set of neighboring pixels reflecting the local property most. From the experimental results, this method shows the effective ambiguity handling capability in segmenting an image.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.209-216
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• 2006

For evaluation of building performance, a nonlinear dynamic capacity of the building is a key parameter. In this study, an reinforced concrete special moment resisting frame building was chosen to study the process of determining the nonlinear dynamic capacity. The building, which was designed by IBC 2003 representing new codes, was composed of special moment resisting frames in the perimeter and internal frames inside the building. The capacity, which is inter-story drift capacity, consists of two categories, local and global collapses. Global collapse capacity was determined by incremental dynamic analysis. Local collapse capacity was determined by the same method except for utilizing damage index. In audition to this, it was also investigated that the effect of including internal frames designed by gravity load in the analysis. Results showed that the damage index is a useful tool for determining local collapse. Furthermore, including the internal frames with special frames in the analysis is very important in determining the capacity of a building so both must be considered at the same time.

• Journal of Korea Multimedia Society
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• v.24 no.3
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• pp.481-493
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• 2021

Regional brands are recognized for their importance as one of the local public relations policies, but only the methods promoted by local government officials and outside experts are revealing limitations in self-reliance and sustainability. In order for a regional brand to succeed, it is necessary to develop and manage a brand that fits the characteristics of the region together with various stakeholders including residents. In this study, it was confirmed that regional brand evaluation indicators may vary depending on the stage of co-creation in the design process for regional brand development, and the type of value co-creation was determined through a classification method using the results of the evaluation index. According to the results of the study, the type of value co-creation that fits the local situation and characteristics can be derived by adjusting the stage of co-creation execution in the design process.

• Journal of Digital Convergence
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• v.16 no.5
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• pp.75-84
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• 2018

The purpose of this study was to analyze the regional distribution of the number of social welfare facilities per 100,000 population by using the concentration index(CI) and to evaluate the relationship with the local welfare environment. The results of the analysis are as follows. First, the distribution of social welfare facilities between urban and rural area were distributed in rural areas. And concentration of rural area was gradually decreasing. Second, the concentration index of the social welfare institution was calculated as the negative index. Therefore, social welfare facilities are concentrated in rural areas. However, the absolute value of concentration index decreased. Finally, there are many social welfare facilities in areas with poor economic conditions, low incomes, low welfare budget input, and poor social demolition indicators. In the future, the relationship between inequality of regional distribution of welfare resources and the relationship between local welfare environment should be continuously monitored.

• Journal of the Korean Mathematical Society
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• v.47 no.2
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• pp.385-407
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• 2010

To study the relationship between the levels of chemical pollutants and the number of daily total hospital admissions for respiratory diseases and to find the effect of temperature/relative humidity on the admission number, Wong et al. [17] introduced the varying-coefficient single-index model (VCSIM). As pointed out, it is a popular multivariate nonparametric fitting technique. However, the tests of the model have not been very well developed. In this paper, based on the estimators obtained by the local linear technique, the average method and the one-step back-fitting technique in the VCSIM, the generalized likelihood ratio (GLR) tests for varying-coefficient parts on the VCSIM are established. Under the null hypotheses the new proposed GLR tests follow the $\chi^2$-distribution asymptotically with scale constant and degree of freedom independent of the nuisance parameters, known as Wilks phenomenon. Simulations are conducted to evaluate the test procedure empirically. A real example is used to illustrate the performance of the testing approach.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.5-6
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• 2015

Recently, freezing index of frost penetration depth estimation used in Korea is applied according to the standard, published by MOLIT in 2003. However, it is difficult to consider can not be determined to standard reflects weather conditions in accordance with the current climate warming or abnormally high temperature. Also the temperature should be considered local variables because heavy local gap. Therefore, this study is through the freezing index presented in MOLIT's code by calculating the frost penetration depth determining whether the adequacy and conducted a study to apply in the field. As a result, when the Elevation 100m to standard in Incheon frost penetration depth is found to be 50.8cm.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.4
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• pp.1-9
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• 2015

The development of drought index that provides detailed-spatial-resolution drought information is essential for improving drought planning and preparedness. The objective of this study was to develop the concept of using satellite-based hybrid drought index called the Vegetation Drought Response Index in South Korea (VegDRI-SKorea) that could improve spatial resolution for monitoring local and regional drought. The VegDRI-SKorea was developed using the Classification And Regression Trees (CART) algorithm based on remote sensing data such as Normalized Difference Vegetation Index (NDVI) from MODIS satellite images, climate drought indices such as Self Calibrating Palmer Drought Severity Index (SC-PDSI) and Standardized Precipitation Index (SPI), and the biophysical data such as land cover, eco region, and soil available water capacity. A case study has been done for the 2012 drought to evaluate the VegDRI-SKorea model for South Korea. The VegDRI-SKorea represented the drought areas from the end of May and to the severe drought at the end of June. Results show that the integration of satellite imageries and various associated data allows us to get improved both spatially and temporally drought information using a data mining technique and get better understanding of drought condition. In addition, VegDRI-SKorea is expected to contribute to monitor the current drought condition for evaluating local and regional drought risk assessment and assisting drought-related decision making.