• Korean Journal of Remote Sensing
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• v.25 no.4
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• pp.321-338
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• 2009

The objective of this paper is to compare spatial prediction capabilities of univariate kriging algorithms for generating GIS-based thematic maps from ground survey data with asymmetric distributions. Four univariate kriging algorithms including traditional ordinary kriging, three non-linear transform-based kriging algorithms such as log-normal kriging, multi-Gaussian kriging and indicator kriging are applied for spatial interpolation of geochemical As and Pb elements. Cross validation based on a leave-one-out approach is applied and then prediction errors are computed. The impact of the sampling density of the ground survey data on the prediction errors are also investigated. Through the case study, indicator kriging showed the smallest prediction errors and superior prediction capabilities of very low and very high values. Other non-linear transform based kriging algorithms yielded better prediction capabilities than traditional ordinary kriging. Log-normal kriging which has been widely applied, however, produced biased estimation results (overall, overestimation). It is expected that such quantitative comparison results would be effectively used for the selection of an optimal kriging algorithm for spatial interpolation of ground survey data with asymmetric distributions.

• Spatial Information Research
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• v.11 no.3
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• pp.251-260
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• 2003

Distribution pattern of seawater intrusion was analyzed from the spatial distribution map of chloride using the geostatistics and CIS analyses. The chloride distribution map made by kriging(ordinary kriging and co-kriging) after exploratory spatial data analysis. Kriging provides an advanced methodology which facilitates quantification of spatial features and enables spatial interpolation. TDS, Na$^{＋}$, Br$^{[-10]}$ were selected as second parameters of co-kriging which is higher value of correlation coefficients between chloride and others groundwater properties. Chloride concentration is highest in yeminchon and coastal area. And result in co-kriging was accurate than ordinary kriging.

• Journal of the Korean Geotechnical Society
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• v.26 no.5
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• pp.57-64
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• 2010

Kriging techniques have been used to estimate the spatial distribution of soil layers and soil properties in the geotechnical engineering area. Since the selected kriging technique may provide different values of estimation, the selection of method is important in the geotechnical estimation. In this paper, the spatial distribution of the thickness of consolidation layer of Songdo International City is estimated using simple, ordinary, and universal kriging techniques, and the reliability of estimated results is analyzed. It is shown that the consolidation layer thickness estimated by the simple kriging technique is larger than those by other kriging techniques when the location of estimation is far from the locations where the measured data exist. In this case, the reliability of the simple kriging technique is observed to be lower than those of other techniques. Universal kriging gives a negative value for thickness of consolidation layer in some locations away from the data. It is concluded that the ordinary kriging is the most optimized estimation technique because the reliability of ordinary kriging technique is higher than those of other ones and the consolidation layer thickness estimated by the ordinary kriging locates within the reasonable range.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.133-133
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• 2018

최근 기후변화로 인해 국지성 호우와 도시화로 인한 불투수율 증가로 내수침수 및 홍수와 같은 피해가 빈번하게 발생하고 있는 추세이다. 이로 인해 강우 관측의 정확도에 대한 논의가 지속되고 있으며, 공간적 분포를 고려할 수 있는 레이더의 활용성이 증가하고 있다. 하지만 레이더 자료는 지상강우 자료와 달리, 반사도와 강우강도 간에 관계식(Z-R 관계식)을 통한 추정치이기 때문에 실제 관측한 지상강우 자료와 함께 보정작업을 수행해야 한다. 본 연구에서는 지구통계학분야에서 제시된 공간 보간법중 하나인 크리깅 기법을 이용하여 강우의 공간적 분포를 추정하였다. 본 연구에서 사용한 크리깅 기법으로는 일반적으로 많이 사용되는 OK(Ordinary Kriging), CK(Co-Kriging), KED(Kriging with External Drift)와 RK(Regression Kriging)기법을 사용하였고, 이를 이용하여 강우장을 생성하고, 생성된 강우장과 레이더값을 비교하였다. 지상강우와 관측소 위치에서의 실제 강우값과 추정된 강우값의 정량적 평가를 실시하였으며, 레이더 강우자료의 공간분포특성과 유사성을 확인하기 위해 각 기법에서의 베리오그램을 비교하였다. 본 연구를 통해 공간적 분포를 고려하여 강우장 분포의 정확도를 높일 수 있었고, 향후 다양한 레이더 보정기법과의 비교를 통해 강우 관측의 정확도를 높일 수 있을 것으로 판단된다.

• Spatial Information Research
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• v.19 no.4
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• pp.81-89
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• 2011

This paper presents a multivariate kriging algorithm that integrates categorical data as secondary data for spatial interpolation of sparsely sampled ground survey data. Instead of using constant mean values in each attribute of categorical data, disaggregated local mean values at target grid points are first estimated by area-to-point kriging and then are used as local mean values in simple kriging with local means. This algorithm is illustrated through a case study of spatial interpolation of a geochemical copper element with geological map data. Cross validation results indicates that the presented algorithm leads to significant respective improvement of 15% and 25% in prediction capability, compared with univariate ordinary kriging and conventional simple kriging with constant mean values. It is expected that the multivariate kriging algorithm applied in this study would be effectively applied for spatial interpolation with categorical data.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.1
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• pp.71-84
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• 2017

Radon, which enters the interior environment from soil, rocks, and groundwater, is a radioactive gas that poses a serious risk to humans. Indoor radon concentrations are measured to investigate the risk of radon gas exposure and reliable radon concentration mapping is then performed for further analysis. In this study, we compared the predictive performance of various univariate kriging algorithms, including ordinary kriging and three nonlinear transform-based kriging algorithms (log-normal, multi-Gaussian, and indicator kriging), for mapping radon concentrations with an asymmetric distribution. To compare and analyze the predictive performance, we carried out jackknife-based validation and analyzed the errors according to the differences in the data intervals and sampling densities. From a case study in South Korea, the overall nonlinear transform-based kriging algorithms showed better predictive performance than ordinary kriging. Among the nonlinear transform-based kriging algorithms, log-normal kriging had the best performance, followed by multi-Gaussian kriging. Ordinary kriging was the best for predicting high values within the spatial pattern. The results from this study are expected to be useful in the selection of kriging algorithms for the spatial prediction of data with an asymmetric distribution.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.188-188
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• 2015

최근 기후변화와 지구온난화로 인한 돌발성 집중호우 및 홍수, 태풍의 빈도 증가는 사회 경제적으로 막대한 피해를 입히고 있다. 수자원 분야에서는 이러한 피해를 예방하고 빠른 대처를 위해 강우의 정밀한 관측뿐만 아니라 강우의 정확한 공간 분포 파악이 요구되고 있다. 그러나 일반적으로 강우의 측정 시 사용되는 지상우량계의 경우 공간적인 밀도가 낮고, 불규칙적으로 위치하고 있어 강우의 시 공간적 변화를 반영하기 어려운 한계가 있다. 이러한 문제를 보완하고자 지상강우자료와 레이더자료를 결합하여 사용하고 있다. 본 연구는 지상강우자료의 양적인 특성을 고려함과 동시에 레이더자료의 공간분포특성을 반영하는 강우장을 추정하고자 하였다. 따라서 지구통계학적 공간보간기법인 크리깅 기법을 적용하였으며, OK(Ordinary Kriging), KED(Kriging with External Drift), ColCOK(Collocated Cokriging) 기법에 의해 생성된 강우장을 비교하였다. 지상강우와의 양적인 측면을 비교하기 위해 관측소 위치에서의 실제 강우값과 추정된 강우값의 상관관계를 비교하였으며, 레이더자료의 공간분포특성과의 유사성을 확인하기 위해 각 기법에서의 베리오그램을 비교하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.8
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• pp.541-548
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• 2019

In this paper, the required amount of heat for an anti-icing system of a Flush Air Data Sensing(FADS) system is predicted. For an efficient prediction during the early stage of a design process, a handbook method is used. A program of which inputs are flight conditions is developed to predict the required amount of heat. A CFD analysis is conducted to compute the water catch efficiency which is one of the core parameters used in the handbook method. Kriging method, one of well-known regression mothods, is utilized to construct a surface contour database to evaluate impingements of droplets. To predict the trajectories of droplets, the database of a flow field around the surface is built using Kriging method as well.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.2
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• pp.101-111
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• 2004

In order to guarantee the stability of a tunnel and its optimum design, it is very important to obtain enough ground investigation data. In realty, however, it is not the case due to the limitation of measuring spatially distributed data and economical reasons. Especially, there are regions where drilling is impossible due to civil appeal and mountainous topology, and it is also difficult to estimate rock mass classes quantitatively with only geophysical exploration data. In this study, therefore, 3 dimensional multiple indicator kriging (3D-MI kriging), which can incorporate geophysical exploration data and drill core data off a tunnel center line, is proposed to cope with such problems. To this end, two dimensional mutiple indicator kriging, which is one of the geostatistical techniques, is extended for three dimensional analysis. Also, the proposed 3D-MI kriging was applied to determine the rock mass classes by RMR system for the design of a Kyungbu express rail way tunnel.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.115-125
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• 2013

This study established a methodology for the application of downscaling technique in a mountainous area having large spatial variations of rainfall and tried to estimate the change of rainfall characteristics in the future under climate change using the established method. The Namhan river basin, which is in the mountainous area of the Korean peninsula, has been chosen as the study area. Artificial Neural Network - Simple Kriging with varying local means (ANN-SKlm) has been built by combining artificial neural network, which is one of the general downscaling techniques, and SKlm technique, which can reflect the geomorphologic characteristics like elevation of the study area. The evaluation of SKlm technique was done by using the monthly rainfalls at six weather stations which KMA(Korea Meteorological Administration) is managing in the basin. The ANN-SKlm technique was compared with the Thiessen technique and ordinary kriging(OK) technique. According to the evaluation result of each technique the SKlm technique showed the best result.