• 해양환경안전학회지
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• 제21권3호
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• pp.253-258
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• 2015

The purpose of this study is to find suitable probability distribution function of complex distribution data like multimodal. Normal distribution is broadly used to assume probability distribution function. However, complex distribution data like multimodal are very hard to be estimated by using normal distribution function only, and there might be errors when other distribution functions including normal distribution function are used. In this study, we experimented to find fit probability distribution function in multimodal area, by using AIS(Automatic Identification System) observation data gathered in Mokpo port for a year of 2013. By using chi-squared statistic, gaussian mixture model(GMM) is the fittest model rather than other distribution functions, such as extreme value, generalized extreme value, logistic, and normal distribution. GMM was found to the fit model regard to multimodal data of maritime traffic flow distribution. Probability density function for collision probability and traffic flow distribution will be calculated much precisely in the future.

• 한국정보처리학회논문지
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• 제3권6호
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• pp.1433-1442
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• 1996

자료 분산은 SPMD(Single Program Multiple Data)형태의 병렬성을 제공하는 HPF (High Performance Fortran)의 주기능으로 구현 방법에 따라 컴파일러 성능을 좌우한 다. 본 논문에서는 SPAX(Scalable Parallel Architecture computer based on X-bar network)상에 자료 분산 기능을 제공하기 위한 설계 주안점과 효율적인 모델에 관하 여 기술하였다. SPAX는 분산공유 메모리 (DSM:distributed shared memory)를 사용한 계층적 클러스터링 구조를 가진다. 이러한 메모리 구조에서는 분산 메모리 자료 분산 (DMDD:Distributed Memory Data Distribution)이나 공유 메모리 자료 분산(SMDD: Shared Memory Data Distribution)방법으로는 시스템 가용성을 만족할 수 없다. 그래 서 계층적 마스터-슬래브 형태의 분산공유 메모리 자료분산(DSMDD:Distributed Shared Memory Data Distribution)모델을 설계하였다. 이 모델은 각 노드에 원격 마 스터와 슬래브들을 할당하고 노드내에서는 공유 메모리를 그리고 노드간에는 메세지 전달 인터페이스를 사용한다. 시뮬레이션을 수행한 결과, 시스템 성능 저하를 최소화 하는 노드 크기로 DSMDD를 수행하였을 때 SMDD나 DMDD보다 훨씬 더 효율적이였다. 특 히, 논리적 프로세서 갯수가 많을수록, 분산된 자료들 간의 자료 종속성이 적을수록 성능이 우수하였다.

• 대한공간정보학회지
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• 제12권3호
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• pp.79-89
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• 2004

민간에 많은 GIS 데이터가 상존하고 있는 대도 불구하고 이에 대한 법적인 대안이나 민간유통의 경로가 없어서 중요한 GIS 데이터가 사장되어 가고 있다. 이러한 문제점을 타개하기 위하여 본 연구에서는 민간GIS유통을 원활하게 하기 위한 민간GIS유통체계에 관한 수요조사 및 분석을 민간기업과 공공기관을 대상으로 시행하여 방안을 제시하였다. 민간GIS유통체계 구축을 위한 수요조사의 결과 민간에서는 민간수요를 충족할 GIS유통기구의 설립 및 운영을 절실히 요구함에 따라 민간GIS 데이터가 원활한 유통이 될 수 있도록 민간GIS유통센터(가칭)구축안을 제시하였다. 수요조사에는 민간기업의 유통관련, 데이터구축 및 관리관련, 법 제도관련, 국가GIS 유통망사업관련, 민간GIS유통센터 설립관련 항목을 선정하여 민간의 적극적 유통참여와 활성화가 요구되었다. 이러한 센터의 구축을 위한3개의 구축모델(민간참여 유도형 모델, 독립 민간GIS 유통센터의 선정모델, 국가GIS 유통망의 기능 분산형 모델)과 3개의 구축 및 운영방안(단계별 구축방안, 재원조달방안, 운영조직방안)이 제시되었으며, 이를 통하여 민간GIS유통센터의 역할 및 유통의 범위를 설정하였다.

• 조명전기설비학회논문지
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• 제27권9호
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• pp.83-89
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• 2013

Power distribution system has been changed from radial system to closed loop or mesh system due to connection of distributed generation growth. Data from distribution equipments which are installed at distribution line is required to be accurate for the performance of DMS(Distribution Management System). This paper analyzes the voltage measurement data from distribution equipment. However, the results of the analysis are confirmed to have some errors in voltage measurement data from distribution equipment. These errors come from aging of voltage sensor in distribution equipment and inaccurate data transfer to FRTU(feeder remote terminal unit) through the controller. The main problem is that the voltage measurement data of distribution equipment can not be assessed after it's first installation at the distribution line. The voltage measurement accuracy assessment system is to assess the voltage measurement data from distribution equipment on hot-line. This study had a field test to verify the performance of system.

• Wind and Structures
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• 제26권6호
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• pp.383-395
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• 2018

An accurate determination of wind speed distribution is the basis for an evaluation of the wind energy potential required to design a wind turbine, so it is important to estimate unknown parameters of wind speed distribution. In this paper, Gumbel distribution is used in modelling wind speed data, and alternative robust estimation methods to estimate its parameters are considered. The methodologies used to obtain the estimators of the parameters are least absolute deviation, weighted least absolute deviation, median/MAD and least median of squares. The performances of the estimators are compared with traditional estimation methods (i.e., maximum likelihood and least squares) according to bias, mean square deviation and total mean square deviation criteria using a Monte-Carlo simulation study for the data with and without outliers. The simulation results show that least median of squares and median/MAD estimators are more efficient than others for data with outliers in many cases. However, median/MAD estimator is not consistent for location parameter of Gumbel distribution in all cases. In real data application, it is firstly demonstrated that Gumbel distribution fits the daily mean wind speed data well and is also better one to model the data than Weibull distribution with respect to the root mean square error and coefficient of determination criteria. Next, the wind data modified by outliers is analysed to show the performance of the proposed estimators by using numerical and graphical methods.

• 품질경영학회지
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• 제46권3호
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• pp.509-522
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• 2018

Purpose: The purpose of this study was to propose more accurate mathematical model which can represent result of government quality assurance activity, especially corrective action and flaw. Methods: The collected data during government quality assurance activity was represented through histogram. To find out which distributions (Poisson distribution, Zero-Inflated Poisson distribution) could represent the histogram better, this study applied Pearson's correlation coefficient. Results: The result of this study is as follows; Histogram of corrective action during past 3 years and Zero-Inflated Poisson distribution had strong relationship that their correlation coefficients was over 0.94. Flaw data could not re-parameterize to Zero-Inflated Poisson distribution because its frequency of flaw occurrence was too small. However, histogram of flaw data during past 3 years and Poisson distribution showed strong relationship that their correlation coefficients was 0.99. Conclusion: Zero-Inflated Poisson distribution represented better than Poisson distribution to demonstrate corrective action histogram. However, in the case of flaw data histogram, Poisson distribution was more accurate than Zero-Inflated Poisson distribution.

• Communications for Statistical Applications and Methods
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• 제23권6호
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• pp.517-529
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• 2016

This study compares the inverse transform and the composition methods for generating data from the Lindley distribution. The expression for the inverse of the distribution function for the Lindley distribution does not exist in closed form. Hence, authors of many empirical studies on the Lindley distribution used methods for generating Lindley variates other than the inverse transform. We generated data from the Lindley distribution using the inverse transform approach by obtaining the Lindley variates numerically; we also generated data from this distribution using the composition approach. Following the generation of the Lindley variates using these two methods, we compare some statistical properties of the estimates of the Lindley model parameters based on the generated data. We conclude that the two methods produce similar results.

• Wind and Structures
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• 제28권6호
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• pp.369-380
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• 2019

Statistical distributions are very useful in describing wind speed characteristics and in predicting wind power potential of a specified region. Although the Weibull distribution is the most popular one in wind energy literature, it does not seem to be able to perfectly fit all the investigated wind speed data in nature. Thus, many studies are still being conducted to find flexible distribution for modelling wind speed data. In this study, we propose a new Odd-Burr Rayleigh distribution for wind speed characterization. The Odd-Burr Rayleigh distribution with two shape parameters is flexible enough to model different shapes of wind speed data and thus it can be an alternative wind speed distribution for the assessment of wind energy potential. Therefore, suitability of the Odd-Burr Rayleigh distribution is investigated on real wind speed data taken from different regions in the South Africa. Numerical results of the conducted analysis confirm that the new Odd-Burr Rayleigh distribution is suitable for modelling most of the considered real wind speed cases and it also can be used for predicting wind power.

• 디지털융복합연구
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• 제14권5호
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• pp.95-106
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• 2016

본 연구는 빅데이터 유통 생태계에 기반한 단계별 빅데이터 유통 모델 개발 방안을 제안한다. 제안하는 빅데이터 유통모델의 개발은 데이터 중개 및 거래 플랫폼 구축, 거래지원 시스템 구축, 데이터 유통 포털 및 빅데이터 거래소 연결망 구축과 같이 3단계로 구성된다. 데이터 중개 및 거래 플랫폼 구축 단계에서는 데이터 유통 및 거래 플랫폼이 구축되며, 총괄시스템과 등록 및 거래관리 시스템으로 구성되며, 거래지원 시스템 구축 단계에서는 원활한 데이터 거래를 위한 거래지원 시스템이 추가적으로 구축된다. 마지막 데이터 유통 포털 및 빅데이터 거래소 연결망 구축 단계에서는 여러 거래소들의 통합에 필요한 유통 관리 시스템이 구축된다. 새로운 기술, 프로세스, 데이터 과학 등을 이용하여 과거의 데이터 관리 시스템을 빠르게 대체해 나가고 있는 현대의 데이터 시장에서 데이터 유통시장 모델은 계속 진화하고 있으며, 비즈니스 업계에서 수용되고 있다. 따라서 제안하는 빅데이터 유통 모델은 멀지 않은 장래에 데이터를 관리하고 접근하기 위한 산업표준 확립 시 고려될 수 있다고 사료된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.201_202
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• 2009

This paper presents a design methodology of a distribution transformer with condition monitoring sensors and its data processing unit. The proposed distribution transformer includes various type of condition monitoring sensors such as load current/voltage, temperature and heat aging of insulating oil. The data processing unit is installed at the distribution transformer site. It integrates sensed data and transmits these to a central server system. The proposed distribution transformer and its data processing unit will help an on-line condition monitoring system for distribution transformers.