• Journal of The Korean Society of Agricultural Engineers
• /
• v.60 no.3
• /
• pp.63-70
• /
• 2018

In this study, a simple probabilistic approach using equivalent coefficient of consolidation ($c_e$) was proposed to consider the spatial variability of coefficient of vertical consolidation ($c_v$), and the effect of the probability distribution of coefficient of consolidation on degree of consolidation in heterogeneous soil was investigated. The statistical characteristics of consolidation coefficient were estimated from 1,226 field data, and four probability distributions (Normal, Log-normal, Gamma, and Weibull) were applied to consider the effect of probability distribution. The random fields of coefficient of consolidation were generated based on Karhunen-Loeve expansion. Then, the equivalent coefficient of consolidation was calculated from the random field and used as the input value of consolidation analysis. As a result, the probabilistic analysis can be performed effectively by separating random field and numerical analysis, and probabilistic analysis was performed using a Latin hypercube Monte Carlo simulation. The results showed that the statistical properties of $c_e$ were changed by the probability distribution and spatial variability of $c_v$, and the probability distribution of $c_v$ has considerable effects on the probabilistic results. There was a large difference of failure probability depend on the probability distribution when the autocorrelation distance was small (i.e., highly heterogeneous soil). Therefore, the selection of a suitable probability distribution of $c_v$ is very important for reliable probabilistic analysis of consolidation.

• KIEAE Journal
• /
• v.16 no.6
• /
• pp.69-75
• /
• 2016

Climate change has resulted in the urban heat island (UHI) effect throughout the globe, contributing to heat-related illness and fatalities. In order to reduce such damage, it is necessary to improve the climate observation network for precise observation of the urban thermal environment and quick UHI forecasting system. Purpose: This study analyzed the effective range of the climate observation network and the distribution of the existing Automatic Weather Stations (AWS) in Seoul to propose optimal locations for additional installment of AWS. Method: First, we performed quality analysis to pinpoint missing values and outliers within the high-density temperature data measured. With the result from the analysis, a spatial autocorrelation structure in the temperature data was tested to draw the effective range and correlation distance for each major time period. Result: As a result, it turned out that the optimal effective range for the climate observation network in Seoul in July was a radius of 2.8 kilometers. Based on this result, population density, and temperature data, we selected the locations for additional installment of AWS. This study is expected to be used to generate urban temperature maps, select and move measurement locations since it is able to suggest valid, specific spatial ranges when the data measured in point is converted into surface data.

• The Korean Journal of Applied Statistics
• /
• v.28 no.2
• /
• pp.231-239
• /
• 2015

A Poisson model is the first choice for counts data. Quasi Poisson or negative binomial models are usually used in cases of over (or under) dispersed data. However, these models might be unsuitable if the data consist of excessive number of zeros (zero inflated data). For zero inflated counts data, Zero Inflated Poisson (ZIP) or Zero Inflated Negative Binomial (ZINB) models are recommended to address the issue. In this paper, we further considered a situation where zero inflated data are spatially correlated. A mixed effect model with random effects that account for spatial autocorrelation is used to fit the data.

• Journal of the Korean Regional Science Association
• /
• v.39 no.2
• /
• pp.31-46
• /
• 2023

This study aims to analyze the spatial patterns of intellectual property across various regions through an in-depth analysis of intellectual property trends and their influential factors. While there's an overall upsurge in intellectual property applications in the Seoul metropolitan areas, a more detailed inspection reveals divergent patterns based on the type of intellectual property - with patent rights primarily increasing in certain non-Seoul areas and trademark rights seeing a rise predominantly within Seoul. Our findings also suggest that the growth in intellectual property applications correlates positively with improvements in public transportation accessibility, expansion of knowledge-based service industries, and a rise in large enterprises, although the relationships vary by intellectual property type. These results indicate the significant influence of geographical factors and industrial structures on knowledge-generation activities, thereby suggesting a need for region-specific policies to bolster these capacities.

• Geophysics and Geophysical Exploration
• /
• v.17 no.1
• /
• pp.11-20
• /
• 2014

To reveal shear-wave velocities ($v_s$) and site characterization of Wonju, Korea, Rayleigh waves were recorded at 78 sites of lower altitude using 12 to 24 4.5-Hz vertical geophones for 20 days during the period of February to September 2013. Dispersion curves of the Rayleigh waves obtained by the extended spatial autocorrelation method were inverted using the damped least-squares method to derive $v_s$ models. From these 1-D models, the average $v_s$ to a depth of 30 m ($v_s30$), $v_s$ of weathered rocks, depths to these basement rocks, and average $v_s$ of the overburden layer were derived to be $16.3{\pm}0.7m$, $576{\pm}8m/s$, $290{\pm}7m/s$, and $418{\pm}13m/s$, respectively, in the 95% confidence range. To determine adequate proxies for $v_s30$, we computed correlation coefficients of $v_s30$ with topographic slope (r = 0.46) and elevation (r = 0.43). An empirical linear relationship is presented as a combination of individually estimated $v_s30$ with weighting factors of 0.45, 0.45, and 0.1 for topographic slope, elevation, and mapped lithology, respectively. Due to a weak correlation between $v_s30$ obtained from inversion of dispersion curves and the proxy-based estimation (r = 0.50), however, the relatively large error range should be considered for applications of this relationship.

• Geophysics and Geophysical Exploration
• /
• v.15 no.1
• /
• pp.1-7
• /
• 2012

To evaluate methods of determining near-surface shear-wave velocities (${\nu}_s$), we derived dispersion curves of Rayleigh waves generated by both passive and active sources in Chuncheon, Korea. Microtremors were recorded for 5 minutes in each of four triangular arrays with radii of 5 ~ 40 m. Those data were analyzed using the Spatial Autocorrelation method. Rayleigh waves were also generated by a hammer source and recorded in the same area for 2 s using 24 4.5-Hz geophones. Multichannel Analysis of Surface Waves was applied to those data. Velocity spectra were derived with relatively high signal-to-noise ratios in the frequency ranges of 7 ~ 19 and 11 ~ 50 Hz for the microtremors and synthetically generated Rayleigh waves, respectively. The resultant dispersion curves were combined as one and then input to inversion to derive shear wave velocities that were compared with a lithology log from a nearby well. Shearwave velocities in the top soil and soft-rock layers are almost constant with values of 221 and 846 m/s, respectively; while the inverse-modeled ${\nu}_s$ increases linearly in the gravelly sand, cobbles, and weathered-rock layers. If rock type is classified based on shear-wave velocity, the inversion-derived boundary between weathered-rock and soft rock may be about 5 m deeper than in the well log.

• Journal of Digital Convergence
• /
• v.19 no.5
• /
• pp.93-103
• /
• 2021

The special means of transportation introduced to improve the mobility of the transportation vulnerable met the number of legal standards in 2016, but lack of development in terms of quality, such as the existence of long waiting times. In order to streamline the operation of special means of transportation, long-term standby traffic, which is the top 25% of the wait time, was extracted from the Daegu Metropolitan Government's special transportation history data, and spatial autocorrelation analysis and social network analysis were conducted. As a result of the analysis, the correlation between the average waiting time of special transportation users and the space was high. As a result of the analysis of internal degree centrality, the peak time zone is mainly visited by general hospitals, while the off-peak time zone shows high long-term waiting demand for visits by lawmakers. The analysis of external degree centrality showed that residential-based traffic demand was high in both peak and off-peak hours. The results of this study are considered to contribute to the improvement of the quality of the operation of special transportation means, and the academic implications and limitations of the study are also presented.

• Journal of Life Science
• /
• v.28 no.2
• /
• pp.148-152
• /
• 2018

The patchiness of local environments within a habitat is assumed to be a primary factor affecting the spatial patterns of plants, and a randomization procedure is developed for testing the null hypothesis that only spatial association with patches determined the spatial patterns of plants. Chloranthus japonicus (Chloranthaceae) is an herbaceous perennial and a member of the genus Chloranthus in the family Chloranthaceae. The spatial pattern of C. japonicus was analyzed according to several patchiness indices, population uniformity or aggregation under different sizes of plots by dispersion indices, and spatial autocorrelation. Population densities (D) varied from 0.356 to 2.270, with a mean of 1.527. The values of dispersion indices ( at Mt. Ahop were lower than 1 at six plots ($2m{\times}2m$, $2m{\times}4m$, $4m{\times}4m$, $4m{\times}8m$, $8m{\times}8m$, and $8m{\times}16m$), but the two large plots ($16m{\times}16m$ and $16m{\times}32m$) were higher than 1. Thus, the aggregation indices ( were negative at Mt. Ahop, which indicates a uniform distribution. The two large plots ($16m{\times}16m$ and $16m{\times}32m$) had positive CIs. However, the values were not large (0.009 for the $16m{\times}16m$ plot and 0.038 for the $16m{\times}32m$ plot). The mean crowding ($M^{\ast}$) and patchiness index (PAI) showed positive values for all plots.

• Spatial Information Research
• /
• v.23 no.5
• /
• pp.31-40
• /
• 2015

The purpose of this paper is to propose a data transformation method for visualizing the statistical information based on the grid system which has regular shape and size. Grid is better solution than administrator boundary or census block to check the distribution of the statistical information and be able to use as a spatial unit on the map flexibly. On the other hand, we need the additional process to convert the various statistical information to grid if we use the current method which is areal interpolation. Therefore, this paper proposes the 3 steps to convert the various statistical information to grid. 1)Geocoding the statistical information, 2)Converting the spatial information through the defining the spatial relationship, 3)Attribute transformation considering the data scale measurement. This method applies to the population density of Seoul to convert to the grid. Especially, spatial autocorrelation is performed to check the consistency of grid display if the reference data is different for same statistic information. As a result, both distribution of grid are similar to each other when the population density data which is represented by census block and building is converted to grid. Through the result of implementation, it is demonstrated to be able to perform the consistent data conversion based on the proposed method.

• The Korean Journal of Ecology
• /
• v.27 no.5
• /
• pp.257-261
• /
• 2004

Juniperus chinensis var. sargentii Henry is a short and creeping evergreen shrub which reaches about 50㎝ in height and occurs in the northeast Asia and in high mountains over the South Korea. Its distribution is restricted, and the number of individuals are gradually decreasing. This study was conducted to estimate spatial pattern, genetic diversity and spatial genetic structure of J. chinensis var. sargentii. A total of 131 clumps were studied in the study area (40m × 60m). The spatial pattern of this population was random (Aggregation index R=1.031). In spite of the small number and the limited distribution, the level of genetic diversity (Shannon's index 1=0.463) was relatively high as compared with those of other plant species with similar ecological characteristics. ISSR genotypes of all individuals were investigated to find the genetic relationship of clumps and genets. Fifteen clumps were composed to be clones, and a total of 116 unique genotypes were composed by separate genets. Spatial autocorrelation analysis using Tanimoto distance showed that the genetic patch was established within 8m. The effect of clonal reproduction on genetic structure was almost nothing.