• Journal of the Korean Data and Information Science Society
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• 제28권1호
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• pp.227-235
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• 2017

When the spatial information of each location is given specifically as coordinates it is popular to use the geographically weighted regression to incorporate the spatial information by assuming that the regression parameters vary spatially across locations. In this paper, we relax the linearity assumption of geographically weighted regression and propose a geographically weighted least squares-support vector machine for estimating geographically weighted mean by using the basic concept of kernel machines. Generalized cross validation function is induced for the model selection. Numerical studies with real datasets have been conducted to compare the performance of proposed method with other methods for predicting geographically weighted mean.

• Journal of the Korean Data and Information Science Society
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• 제27권5호
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• pp.1225-1239
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• 2016

We investigate pediatric tumor incidence data collected by the Florida Association for Pediatric Tumor program using various models commonly used in disease mapping analysis. Particularly, we consider Poisson normal models with various conditional autoregressive structure for spatial dependence, a zero-in ated component to capture excess zero counts and a spatio-temporal model to capture spatial and temporal dependence, together. We found that intrinsic conditional autoregressive model provides the smallest Deviance Information Criterion (DIC) among the models when only spatial dependence is considered. On the other hand, adding an autoregressive structure over time decreases DIC over the model without time dependence component. We adopt weighted ranks squared error loss to identify high risk regions which provides similar results with other researchers who have worked on the same data set (e.g. Zhang et al., 2014; Wang and Rodriguez, 2014). Our results, thus, provide additional statistical support on those identied high risk regions discovered by the other researchers.

• Communications for Statistical Applications and Methods
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• 제28권4호
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• pp.315-327
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• 2021

The Spatial Autoregressive (SAR) models have drawn considerable attention in recent econometrics literature because of their capability to model the spatial spill overs in a feasible way. While considering the Bayesian analysis of these models, one may face the problem of lack of robustness with respect to underlying prior assumptions. The generalized Bayes estimators provide a viable alternative to incorporate prior belief and are more robust with respect to underlying prior assumptions. The present paper considers the SAR model with a set of linear restrictions binding the regression coefficients and derives restricted generalized Bayes estimator for the coefficients vector. The minimaxity of the restricted generalized Bayes estimator has been established. Using a simulation study, it has been demonstrated that the estimator dominates the restricted least squares as well as restricted Stein rule estimators.

• Investigative Magnetic Resonance Imaging
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• 제16권2호
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• pp.115-123
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• 2012

목적: Tract-based spatial statistics와 화소기반 형태분석 방법을 이용하여 경도의 알츠하이머병 환자와 경도인 지장애 환자에서 확산텐서영상을 이용하여 뇌 백질의 이상을 평가하고자 하였다. 대상과 방법: 21명의 경도의 알츠하이머병 환자와 13명의 경도인지장애 환자, 그리고 16명의 건강한 노인군을 대상으로 확산텐서영상을 시행하였다. 각 참가자마다 분할 비등방도를 구하여 Tract-based spatial statistics를 이용하여 세 그룹간의 비교를 하였다. Tract-based spatial statistics 방법과의 비교를 위하여, 화소기반 형태분석 방법을 이용한 분석도 함께 시행하였다. 결과: Tract-based spatial statistics 분석결과, 경도의 알츠하이머 환자에서 건강한 노인군보다 방사관의 양측 전각과 우측 후각, 후시상방사, 우측 상세로다발, 뇌량체부, 우측 쐐기전소엽이랑에서 분할 비등방도가 유의하게 감소하였다. 화소기반 형태분석에서는 양측 갈고리다발, 좌측 부해마회의 백질, 우측 대상다발에서 추가적으로 분할 비등 방도가 감소되어 있었다. 경도의 알츠하이머 환자군과 경도인지장애 환자군의 비교, 경도인지장애 환자군과 건강한 노인군의 비교연구에서는 분할 비등방도의 유의한 차이는 없었다. 결론: Tract-based spatial statistics 분석결과, 경도의 알츠하이머 환자군에서 건강한 노인군에 비해 뇌 백질의 분할 비등방도가 여러 곳에서 감소되어 있었다. 화소기반 형태분석방법은 tract-based spatial statistics보다 더 많은 곳에서 뇌 백질의 이상을 보였다. 그러나, 인공물 또한 더 많이 관찰되었다.

• Journal of the Korean Statistical Society
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• 제30권4호
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• pp.573-583
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• 2001

A condition in which the covariances of Matheron's variogram estimators are expressed in a simple form is reviewed. An asymptotic property of the covariances of the variogram estimators is examined, and a sufficient condition that guaranties the finiteness of the asymptotic variance of the normalized variogram estimators is provided.

• 응용통계연구
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• 제30권3호
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• pp.311-321
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• 2017

주성분 분석은 통계학 뿐만 아니라 기상학에서 널리 사용되는 방법론이며, 고차원 자료에 대한 차원축소 역할 뿐만아니라 기상자료에서의 의미있는 패턴을 찾아내기 위해 사용되는 방법론이다. 또한 주성분분석에 기반을 둔 주성분 회귀분석 방법론은 기후예측이 가능하므로 미래 시점의 기후값 예측에 사용될 수 있다. 본 논문에서는 Wang과 Huang (2016) 논문에서 제안한 제한된 공간 주성분 분석을 기반으로 한 주성분 회귀분석 방법론을 개발하였다. 이를 시뮬레이션을 통하여 확인하였고, 실제 자료인 동아시아 지역 온도예측에 적용하여 기존의 주성분 회귀분석 예측 값에 비해 예측력이 높아짐을 확인하였다.

• Journal of Multimedia Information System
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• 제4권2호
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• pp.89-92
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• 2017

This paper investigates simple gray level image enhancement technique based on Genetic Algorithms and Local Statistics. The task of GA is to adapt the parameters of local sliding masks over pixels, finding out the best parameters preserving the brightness and possibly preventing the creation of intensity artifacts in the local area of images. The algorithm is controlled by GA as to enhance the contrast and details in the images automatically according to an object fitness criterion. Results obtained in terms of subjective and objective evaluations, show the plausibility of the method suggested here.

• 응용통계연구
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• 제23권2호
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• pp.335-344
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• 2010

공간자료분석에서 공간적 상관성을 배제한 일반적인 회귀모형을 통한 모수 추정값들은 신뢰성의 문제가 지적 되어 오고 있다. 본 연구에서는 공간자료의 상관성을 고려한 모형을 구축하기 위하여 일변량 조건부자기회귀모형을 이용하였으며 베이지안 기법을 통하여 모수를 추정하고 공간상관성이 고려된 공간 가산자료모형과 고려되지 않은 일반 가산자료모형을 비교하였다. 연구 대상으로는 서울시의 25개 행정자치구별 총범죄 자료를 이용하였으며 자료분석을 통하여 도시계획과 같은 국가 정책의 수립에 참고자료로 활용될 수 있으리라 판단된다.

• 보건행정학회지
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• 제23권4호
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• pp.387-396
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• 2013

Background: The purpose of this study was to analyze the association between areas of Korea Train Express (KTX) region and external medical service use in Korean society using spatial statistical model. Methods: The data which was used in this study was extracted from 2011 regional health care utilization statistics and health insurance key statistics from National Health Insurance Corporation. A total spatial units of 229 districts (si-gun-gu) were included in this study and spatial area was all parts of the country excepted Jeju, Ulleungdo island. We conducted Kruskal-Wallis test, correlation, Moran's I and hot-spot analysis. And after, ordinary linear regression, spatial lag, spatial error analysis was performed in order to find factors which were associated with external medical service use. The data was processed by SAS ver. 9.1 and Geoda095i (windows). Results: Moran's I of health insurance patients' external medical service use was 0.644. Also, population density, Seoul region, doctor factors positively associated with health insurance patients' external medical service. In contrast, average age, health care organization per 100 thousand were negatively associated with health insurance patients' external medical service use. Conclusion: The finding of this study suggested that health insurance patient's external medical service use correlated for seoul region in korea. The study results imply the need for more attention medical needs in the region (si-gun-gu unit) for health insurance patients of seoul region. It is important to adapt strategy to activation of primary health care as well as enhancing public health institution for prevent leakage of patients to other areas.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.61-64
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• 2005

The purpose of this paper is to take a closer look at an area having shorted emergence facilities and to determine optional candidate sites instead of vulnerable area by using GIS spatial analysis. Newly determined new candidate is performed by concerning spatial efficiency and spatial equity for a public service. It was determined through using the analyzing of the physical accessibility measure, the Location-Allocation, sort of classic model in spatial statistics and general network analysis. The area of this research has been used in administrative boundary of Young-Dong in Gangneung including 13 emergency, medical hospitals, 46 fire-stations and sub-fire stations. In general terms, what all this show is that the way we are approached for geographical view from using GIS spatial analyzing technique of determined location and allocation problem by the social, economical, political factor and simple administrative discrimination at the meantime. At the same time, with problem occurred in the space it is possible to make an Effective proposal or means, policy, decision for new candidate location-allocation suggesting optimum model.