• The Korean Journal of Applied Statistics
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• v.23 no.2
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• pp.375-382
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• 2010

In this study, we propose a robust estimator of the multivariate location parameter by means of the spatial median based on data trimming which extending trimmed mean in the univariate setup. The trimming quantity of this estimator is determined by the bootstrap method, and its covariance matrix is estimated by using the double bootstrap method. This extends the work of Jhun et al. (1993) to the multivariate case. Monte Carlo study shows that the proposed trimmed spatial median estimator yields better efficiency than a spatial median, while its covariance matrix based on double bootstrap overcomes the under-estimating problem occurred on single bootstrap method.

• The Korean Journal of Applied Statistics
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• v.22 no.4
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• pp.677-686
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• 2009

Stratification of population is widely used to improve the efficiency of the estimation in a sample survey. However, it causes several problems when there are some variables containing outliers. To overcome these problems, Park and Yun (2008) proposed a rather subjective method, which finds outliers before $\kappa$-means clustering for stratification. In this study, we propose the $\kappa$-spatial medians clustering method which is more robust than $\kappa$-means clustering method and also does not need the process of finding outliers in advance. We investigate the characteristics of the proposed method through a case study used in Park and Yun (2008) and confirm the efficiency of the proposed method.

• Proceedings of the Korean Statistical Society Conference
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• 2003.05a
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• pp.275-280
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• 2003

공간 자료에서 이상점이 존재할 경우 변이도(Variogram)를 추정함에 있어 그 효과를 줄이기 위한 방법으로 로버스트(robust) 변이도를 이용한다. 그러나 이상점이 존재하는 자료분석에서 로버스트 변이도를 사용하기에 앞서 이상점을 수정한 자료를 사용하였을 경우 그 효율성 또한 좋다고 알려져 있다. 본 논문에서는 이상점이 존재하는 자료를 분석함에 있어 기존의 이상점 수정법 및 새로운 이상점 수정법의 효율성을 비교하였다.

• The Korean Journal of Applied Statistics
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• v.17 no.2
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• pp.327-336
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• 2004

Many researchers have used the robust variogram to reduce the effect of outliers in spatial data analysis. Recently it is known that estimating the variogram after replacing outliers is more efficient. In this paper, we suggest a new data cleaner for geostatistic data analysis and compare the efficiency of outlier cleaners.

• Journal of Elementary Mathematics Education in Korea
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• v.13 no.1
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• pp.97-114
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• 2009

The purpose of this study was to investigate the effects of digital mathematics textbook on spatial abilities, interest and achievement of 6th graders. For this, research questions were set as follow: A. Is there any difference in cognitive ability in the space perception test between the experimental group and the control group. B. What distinctive attributes exist between the experimental group and the control group in the Spatial abilities? C. Is there any difference in learners' interest and achievement between the experiment group and the control group. To investigate the research questions, two classes of 6th grade children were selected from an elementary school in Daejeon and assigned one as experimental group and the other as control group. The experimental group studied mathematics using Digital Textbooks under an individual PC environment while the control group studied using the existing book-type textbooks. The following results and conclusions were obtained from the research. First, the effect of the Digital Textbooks on children's mathematics achievement was not statistically meaningful even though there was some progress in children's achievement. Furthermore, it was not found that the usage of a Digital Textbooks consistently influenced improvement in the students' interest in mathematics. Second, there were some positive changes in the achievement of Spatial ability of the middle subgroup of pretest score in the experiment group. It can have some educational implication that the Digital Textbooks can affect positively to the middle group in mathematics achievement who dominated more than 50% of the class. Third, the number of correct answers was found to be somewhat higher than that of the control group in spatial reasoning items. This means that the learning environment with Digital Textbooks allow more opportunities for manipulating geometric objects physically and mentally. Therefore, It seems necessary to offer various resources such as digital contents for students' geometric learning. For future research, It is strongly recommended to fix the bugs of the digital textbook programs and to upgrade the operating system of the computer.

• Journal of Korean Home Economics Education Association
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• v.16 no.4 s.34
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• pp.81-94
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• 2004

The purpose of this study was to research middle school students' interest and practice about the housing education contents in Technology and Home Economics Subject(classify them into three units, application of living space, indoor environment and equipments. support and repair of housing) in their real life. This was the investigation of which 529 middle school students have lived in Jeonbuk province, SPSS program was utilized to analyze percentage. mean and standard deviation. as well as t-test, One-Way ANOVA and Pearson's correlation coefficients. The results of this research were as follows: Middle school students' interest and practice of the housing education contents appeared to the middle level. Middle school students was consider that the order of interest parts of housing contents were indoor environment and equipments. application of living space, support and repair of housing. And the order of practice parts of housing contents were application of living space. indoor environment and equipments. support and repair of housing. There were significant differences in interest and practice of contents according to demographic variables such as sex, educational level of parents, social status of home. school record. Interest about the housing education contents had significant positive relationships with practices of contents of housing education. Therefore. it would be necessary to develop teaching materials and housing education contents promoting interest of students.

• 한국공간정보시스템학회:학술대회논문집
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• 2007.06a
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• pp.37-42
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• 2007

이 연구는 u-City의 성공적 조성을 위해 u-서비스 공급자 측면과 수요자 측면의 요구를 충족할 수 있는 u-서비스 우선순위 선정에 관한 체계적 연구의 필요성에서 시작되었다. u-서비스 우선순위 모형개발을 위해 선행 연구를 토대로 수요자와 공급자의 서비스 결정 요인을 탐색적으로 도출하고, 전문가와의 브레인스토밍을 통해 u-서비스 결정의 확정적 요인을 도출하였다. 도출된 요인들을 계층분석(AHP)모형으로 설정하고, 1차 전문가 설문조사를 통해 요인별 가중치와 우선순위를 도출함으로써 공급자와 수요자를 고려한 u-서비스 우선순위 선정 모형을 제시하였다. 개발된 모형을 바탕으로 2차 전문가 설문조사를 통해 u-지역정보화에서 제시한 대구지역의 특화서비스를 평가하였다. 평가 결과 대구지역은 지역물류 지원서비스, 시각장애인 길안내 서비스, u-텔레매틱스 서비스가 상위권을 차지한 반면, u-지역정보화에서 제시한 안전방재지원서비스와 산업특화거리 등의 서비스는 중위권을 차지하고 있어 공급자 위주의 u-서비스 선정과는 차별성을 보였다. 개발된 u-서비스 우선순위선정 모형은 u-서비스 제공 및 사용의도에 기반한 모형으로 u-서비스 우선순위 선정을 체계적으로 지원할 수 있어 향후 성공적 u-City 조성에 기여할 수 있을 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.236-236
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• 2016

현재 댐운영 계획 수립 시 매월 유지해야 하는 저수량의 범위를 나타낸 기준수위가 사용되고 있으며 매년 홍수기 말에 현재의 수문 상황과 장래의 전망을 통한 시기별 연간, 월간 댐운영 계획을 수립하고 있다. 물관리의 이수측면에서 댐수위 운영계획 수립과 홍수기 운영목표 수위를 결정하는데 활용하기 위해서는 계절단위, 연단위의 기상정보가 필요하다. 본 연구에서는 기상청에서 운영하고 제공하는 전지구 계절예측시스템 GloSea5(Global Seasonal forecasting system version 5)자료를 활용하여 금강유역에 적용하고자 하였다. GloSea5는 전지구계절예측시스템으로 대기(UM), 지면(JULES), 해양(NEMO), 해빙(CICE)모델이 서로 결합되어 하나의 시스템으로 구성되어 있으며 공간 수평해상도는 N216($0.83^{\circ}{\times}0.56^{\circ}$)으로 중위도에서 약60km이다. Hindcast자료는 유럽중기예보센터(ECMWF)에서 생산된 ERA-Interim 재분석장을 대기 모델의 초기장으로 사용하며 기간은 1996~2009년의 총 14년이다. 예보자료의 검증은 예보의 질을 결정하는 과정으로 Brier Skill Score (BSS), Reliability Diagrams, Relative Operating, Characteristics (ROC)등을 통해 정확성과 오차에 의한 예보의 성능을 검증하였다. 또한 Glosea5의 통계적 상세화를 수행하여 다양한 변수가 갖는 계통적인 지역 오차를 보정함으로써 자료의 신뢰도를 향상시키고자 하였으며 이는 이후 수문모델과의 연계 시 보다 정확하고 효율적인 댐운영에 활용할 수 있는 기후예측정보를 제공할 수 있을 것으로 판단된다.

• Journal of Environmental Science International
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• v.5 no.5
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• pp.619-633
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• 1996

Intraseasonal variability of the tropical convection over the Indian/western Pacific is studied using the Geostationary Meteorological Satellite high cloud amount. This study is directed to find the tropical-extratropical interaction in the frequency range of intraseasonal and interannual variabilities of the summer monsoon occured over the domain of 90E-171W and 495-50N. Especially, in order to investigate the intraseasonal interaction of last Asia summer monsoon associated with the tropical convections in the high cloud amounts, the spatial and time structure of the intraseasonal oscillation for the movement-and the evolution of the large-scale connections are studied. To describe the spatial and the time evolution, the extended empirical orthogonal function analysis is applied. The first mode may be considered to a normal structure, indicating that the strong convection band over 90E-120E is extended to sastward but this mode was detected as the intraseasonal variability during summer monsoon. It is found that the dominant intraseasonal mode of the tropical convection consists of the spatial changes over a broad period range centered around 40~50days.

• The Korean Journal of Applied Statistics
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• v.22 no.6
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• pp.1355-1364
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• 2009

This work propose a robust test for location parameters in multivariate data based on MVE and MCD with the affine equivariance and the high-breakdown properties. We consider the hypothesis testing satisfying high efficiency and high test power simultaneously to bring in the one-step reweighting procedure upon high-breakdown estimators, which generally suffer from the low efficiency and, as a result, usually used only in the exploratory analysis. Monte Carlo study shows that the suggested method retains nominal significance levels and higher testing power without regard to various population distributions than a Hotelling's $T^2$ test. In an example, a data set containing known outliers does not make an influence toward our proposal, while it renders a Hotelling's $T^2$ useless.